I do still think it messes up the balance. I'd rather have Aradin just die than to have the game unbalanced with all of its extremes.
One thing leads to another. Allow potions as Bonus instead of Action, and allow throwing potions, and you have to tweak clerics to make them better healers so they're worth something, which then allows wizards to cast two spells in a single turn which makes them more powerful at higher levels. Also, potions as Bonus negates Rogue Fast Hands special ability's most potent mechanic, allowing Rogues to use potions as a Bonus. So, then to make Fast Hands better, you have to add homebrew to it, or it becomes almost worthless, so they make it so you can do a Second Bonus action, which means Rogue can do 3 attacks in a round with two weapons. This then makes Rogues more effective melee fighters than fighters, so you need to add more fighter attack options to make them more versatile close rangers, thus weapons receive more melee options, and since fighters can use all weapons they now have more options in melee to try to offset the fact that other classes are now pretty much just as good as they are at fighting.
It's a chain reaction that could go on and on and on and on.
Honestly, even with the mechanic of drinking a potion being a bonus action (which isn't that unusual to me as the DMs I interact with rule it as a BA) and the ability to throw potions as such (which I agree is weird mechanic in table top sessions I have played you can certainly throw a potion to some one but that requires a DEX check both for the person to throw and for it to be caught thus eating a BA for the thrower and reaction for the catcher and then the catcher has to wait till their turn and use a BA to drink it), I don't think the change to casting was needed to make healers relevant and I am not 100% sure that is why Larian made it (Sorry not a mind reader :P ). Fact is as far as we know there are only the two types of healing potions the common variety (which you do admittedly get access to way more than I am used to seeing in a campaign) and greater (which ironically doesn't seem to be in the 5e books or at least is missing from D&D Beyond) which combined with the game mechanics certainly renders healing word and cure wounds far less useful in early game play... but the healing you get from spells eventually starts to out pace the healing you get from potions, obviously Cure Wounds out paces the healing from potions a lot faster than healing word, but unless you are a Life Cleric healing word really doesn't improve much at higher levels.
Just an example at lvl 4
the potential healing from a healing potion (2d4+2) has a range of 4-10 hp
However a second level healing word (2d4+spell casting mod) CAN be (if you took the ASI and dependent on race) 2d4+4 which means your healing range is 6-12 ...not much of an improvement but some... then of course if you are playing the best healer (IMHO) a Life Cleric it then becomes 2d4+SCM+2+Spell Level (in this case 2d4+4+2+2) which makes the range of your healing 10-16 which puts it just slightly behind a potion of greater healing (4d4+4) with a range of 8-20.
However casting a second level Cure Wounds -which should should be done instead of healing word whenever possible- (2d8+SCM) will typically out pace potions... using the example above it would be 2d8+4 which means the healing range would be 6-20 which puts it pretty much on pace with a potion of greater healing, but wait there is still more... lets bring back our friend the Life Cleric this increases the healing potential by a much wider margin (2d8+4+2+2) healing range of 10-24 which is better than a Potion of Greater healing... maybe not by much... but still better...
So then we get in to as you reach higher levels (once we are no longer capped at lvl 4) as you progress and you SCM potential gets higher (maxing out at +5) and your ability to cast healing spells at higher levels comes in to play you find that using a healing spell will give you more bang than a potion, once again this is particularly true with Life Clerics and tbh when it comes to party healing potions aside IMHO you have two choices multiple characters (at least 2) who have some moderate-decent ability to heal others such as a Cleric of any domain other than Life and a Druid or Bard (I didn't add Paladin because In My experience it has been that Paladin focuses their healing on themselves so as to give the healer one less person to worry about) or a dedicated healer like a Life Domain Cleric (I am not super familiar with Bards and Druids... so if there is a subclass of either that similarly has extra healing BS that puts them on par with a Life Cleric feel free to let me know)
TLDR; healing at higher levels will start to out pace potions, particularly in the case of the Life Domain Cleric- Life Cleric=Best Healer
