1. 5e uses Bound Accuracy, so a +1 is 5% and that's a lot more than you seem to think it is, especially as enemies get more AC and higher saves. There's a reason Proficiency takes so long to get up and you can't normally start with an 18 in any stat and it takes 4 entire levels for most classes to get more ASI's. It's also a difference in number of spells prepared, saving throws, and in the case of Dexterity for noncasters, AC, initiative, saves, stealth, and for some even accuracy and damage. +1 is a huge deal, that's why we love +1 weapons, +1 armor, artificers in 5e using +1 spell foci, the PHB and DMG originally left out +1 foci from the game because they were afraid they would be too strong. They added them later, but even then, most DMs will give out a +3 greatsword before giving the wizard a +2 spell focus. Cantrips cause status effects, slowing enemies with Ray of Frost, stopping healing from Chill Touch, Preventing reactions with Shocking Grasp. A lot of your most basic attack options can make a huge impact when they hit, so you want them to hit, so that 5% in the long game is a huge deal because you use that 5% almost every single action, reaction, and bonus action that is relevant which adds up very quickly. If it's important for even your cantrips to succeed, imagine having your spell slots fail you. A lot of status require multiple saving throws, like hold or charm person, so each saving throw tests that 5% chance on even a single spell, so sometimes that 5% is applied two or three times in a single round. It's a lot.
In pathfinder 2e a +1 is actually not a very big deal since you add your level to everything... so I have to VERY strongly disagree there. I don't care about about losing a +1 in favor of having a little more charisma to make a fun character in Pathfinder 2e. Having played both systems twice a week for years now, +1 is a way bigger deal in 5e than in most other systems. I say this as a player and a DM. 5% alone may not seem like a lot on a single roll. 5% 15 times in a single fight is a lot. 5% for 8 levels is definitely an absolute ton. You need to have some forward thinking to see how many times that 5% made you fail.
1. As I stated previously, +5% matters in terms of average effectiveness more the lower the chance is (to a point of hoping for 20). If you are trying to hit an enemy with high AC and need a roll of 17-20, that +1 is massive in terms of DPR or duration of an effect. But in those cases it is ALWAYS better to look for another option other than rolling those odds. So in actual play if that 5% actually matters to a massive degree (like 30% increased effectiveness) it's more on the player for choosing wrong action or on the team not supporting a player to do it's job than on single stat point. Additionally 15 Int Wizard would most likely have higher CON or DEX due to his racial bonus, which will make surviving an opportunity attack after the 1/20 failed shocking grasp more likely. +1 in main stat without getting anything else is obviously good, but we are not talking about that. Choosing a race that doesn't allow you to get +3 modifier in your main stat does not mean that it doesn't have other strengths. And a player can use those strengths in new interesting way that go beyond what a usual exemplar of its class is capable of and thus minimizing the impact of lack of +1 to a stat point.
For some people, if the option to be overpowered exists, they cannot allow themselves to take anything less. I, for example, actually really like high charisma or intelligence Barbarians, which is sub-optimal because Wisdom then falls off and I have a weak saving throw, so I am sort of hurting myself there, and when I tell people at my tables that's what I want to play and end up with a 14 in Charisma they give me a weird side eye like having the overpowered option of picking Variant Human and having 17 str 16 con 14 dex and 14 wis was possible and picking either GWM or Resilliant: Wisdom was possible, so why am I a Tiefling who can't cast spells while raging, dropping wisdom, and picking up a stat that's never used in combat? Well, because it's fun, but some people can't bring themselves to do that. I just want to play as Gorge, the Half Orc negotiator who is definitely capable of handling it if the negotiations go south, instead of Gorge, the half orc in the back that stays there until things to bad. He fight good and that all he do, that's boring.
I guess what I'm saying is it can remove the fun for some people because they will only ever create a character that has the best stats for their role and blame the possibility of min-maxing on their actual min-maxing, which isn't how it works at all, if you think min-maxing removes creativity, just... don't do it? But not everyone thinks like that. If they can, they will feel compelled to. That's why maybe when you click New Game you can just opt in, since mods will add it anyway this functionally makes it an Opt In anyway, even though it being on by default is also opt in since when you change race the game can just automatically select the default ASI... The character Elebhra is describing still exists, which is ironic because they are also saying they wouldn't do it if they could do something better, but a dexterous wizard can still be a fun thematic choice especially if they impliment GFB or other such cantrips so their weapon damage with daggers does scale up, you'd just be opting into it as opposed to being forced into it, and like I said, some people cannot bring themselves to opt into weaker choices for the sake of thematics, roleplay, or fun.
Of note, floating ability scores also opens more roleplay options like a nerdy Barbarian or such builds without being human, since you may just want a +1 to 3 stats. I would be choosing to remove optimization in favor of roleplaying options.
Race Identity is not the problem. Limiting thematics and roleplay fantasies is. Player agency for what they want to play. If they want to powerplay? Fine. If they don't? Also fine. But as an advocate of player choice, roleplay, and thematic choices, I have to say choosing stats is important, roleplayers and min-maxers alike will mod the feature in anyway, so why not just build it into the game? If you don't want to do it, just... don't?
Do you really need floating stat points to make a nerdy barbarian dwarf? Just put as many point into intelligence as possible. Why the need to give yourself even more? Can you roleplay better with it? Half-orc with 10 strength will be considered weak, do you really need 8 for your character fantasy?
I find hard to believe that anyone who considers a role play a big factor needs floating stat point to create a unique character.
1. Losing +1 modifier for main spell-casting stat is not "shooting yourself in a foot". You massively overstate the importance of having a +3 instead of +2. It's more visible for martials, but it's never character breaking. 16 int wizard being great and 15 int wizard sucking is just not true. In cases when it would made a massive difference you probably shouldn't rely on DC spells anyway (+1 to DC matters a lot when your chance of actually beating their save is low, meaning you probably should do something else). In 3.5e or Pathfinder the difference is a lot bigger since a lot of class features scale with your main stat, 5e is a different beast.
Yes, of course it is shooting yourself in the foot. A higher number has an impact. That's a fact, it's not in dispute at all. You're just arguing that being shot in the foot isn't as bad as I think. It's irrelevant that other systems have shooting yourself in the foot be much worse. We're not talking about other systems. We're talking about 5e.
3. Floating stat bonus doesn't really prevent you from feeling penalized. Why would you play a High Elf or Tiefling wizard when you could play a Shield Dwarf with the same stats and additionally use medium armor. Why would you ever play any other race than Drow as ranged character? That darkvision increase is incredible. Why would you play a frontline that is not Gold Dwarf for that toughness. Or Barbarian or Champion that is not a half-orc...
It doesn't fix a supposed problem while ruining race identity,
Because if I want to play as a High Elf or Tiefling wizard, I want to play as a High Elf or Tiefling Wizard and not a Shield Dwarf wizard. Those are different characters, even though they're both wizards.
You talk about how floating ASI's destroy the identity of races? Where the +2/+1 goes is the LEAST interesting thing about a race.
My idea for a pen-and-paper Halfling Wizard doesn't start out by first taking 1 level in Artificer before going full Wizard, even though that would be more mechanically advantageous. Based on that character's personality, history, and circumstances, it does not make sense for them to take a level in Artificer, so they wouldn't do that.
So on one hand whatever the impact is, big or small, it doesn't matter because it still prevents you from playing a race-class combination you want. So you need to float those racial stat points.
But on the other hand the racial abilities don't matter, because whatever the impact, they have you still will play a race-class combination you want.
I find those two a little bit contradictory.
By continuing to ignore my question about how your fun would be impacted, it proves you have no answer. That shows that my argument is correct.
I asked you in return if allowing free points at character creation wouldn't be a solution. Whatever answer you would give to that question is the same answer I would give to yours. How is your fun impacted by someone wanting to roll until he gets al 18s or edits that in?
If someone finds fun in playing a character with +5 to everything who are you to tell them you shouldn't have fun like that.
There's a difference between being able to put a +2/+1 where you want and being able to type in a +4 to everything.
But the severity of it's impact doesn't matter (see above) as long as you can't prove that it undeniably ruins your personal fun, right?