1. Bards get expertise too.
Aye, but there are other factors that combine. Like, other classes are simple, such as Fighter where you can go Champion and you just need to slap things and stack Str + Con, but they don't get Expertise.
Bard has their spells to manage, their Bardic Inspirations to manage, their dual focused stats to manage...
While Rogue is nice and simple.
2. Disagree about spell usage, because almost any player is going to need to get to grips with that anyway. At least if they use Gale, Wyll, or Shadowheart. Unless they are deliberately aiming for a no magic run or something, which would probably be very challenging.
Aye. But if someone picks bad spells on a companion and they feel the companion isn't pulling their weight, they can swap to a different companion. If someone picks bad spells on their main character... They're stuck being ineffective.
Sure, Withers exists to respec stuff, but not every new player knows about Withers nor chooses to utilize it.
3. Cunning actions are useful and necessary for character that needs to do a lot tactical maneuvering on the battlefield. I find rouges to need more careful positioning to be effective than some other classes.
Cunning Actions are useful no matter what class you are. Having these tools is pretty nice.
Rogues don't need any more careful positioning than any other class. At best they need another character to posiition well... But having a Tank character go stand by an enemy is pretty easy to do. (It's not like this is earlier editions of DnD where Sneak Attack required enemies to be "Flanked" meaning at least 2 allies near them or that Sneak Attack is melee only unless obtaining special subclass bonuses to enable it for thrown/ranged weapons)
If anything they often need LESS careful positioning than other classes. Given that most spell capable classes utilize Concentration spells which require you to avoid being hit to not have to make Concentration saves to keep the spell active.
4. Fair, but plenty of classes aren’t much worse. Paladin’s might be the trickiest, usually needing strength, constitution, charisma and probably some dex.
It depends. Bard for example, needs Chr (For their spells) + Dex/Str (For their weapons). Most characters want a healthy amount of Dex anyway for initiative and AC (So things like Wizards, Sorcerers, Fighters, Barbarians etc. Are wanting at least some amount of their Primary stat + Con + Dex. While Rogue is literally just Dex + Con)
5. I probably would actually. I think most new players would aim to recruit as many companions as possible. They might only play once and probably want to see most of the game. Killing major characters off for role playing reasons seems more a thing for subsequent play throughs to me.
I've been around long enough to note that people don't always play like I would. Some will avoid Gale entirely because "Portal is scary". Some might kill Astarion (I mean, given his literal first appearance is him holding a dagger to your throat unless you pass the skill check...). Some people simply don't go to every single location on the map and might not find Astarion standing around.
What I wouldn’t assume is that the OP is asking for the easiest class to play. Or that they don’t want to worry about using spells, or finding equipment that works well with their choice. They probably just don’t want to pick something that people generally agree is crap. I don’t think there are any such classes, btw.
Yeah, but I've seen plenty of new players get confused about mechanics and stuff and be overwhelmed by the vast amounts of choices one can make. Hence, why I tend to reccomend something easier to play to learn the ropes. Get the basic systems down and functionalities and then look into the more complex resource management systems of other classes.
Because if someone really likes Astarion and wants them in the party, having two rouges could be a bit limiting.
I don't feel that having two (Or three or even four) Rogues in a party to be limiting at all. Such is the nature of 5e, there isn't the much in the way of limitations (Like, you don't NEED a Rogue to disarm traps. You don't NEED a Wizard to use scrolls. You don't NEED a Cleric to use Revivify) even more so with BG3's penchant for throwing potions and scrolls and magical items at you like there's no tomorrow.
At the end of the day, yes, there are more effective classes in the game. Bard is very versatile for example, Fighter and Monk can be utterly broken etc. But the thought process behind my suggestion of Rogue, is someone who's new to the series might want to be eased into the games systems. Which Rogue does excellently given its reasonably high effectiveness while being simple to build and play.
You're welcome to suggest other classes to new players for other reasons, but these are my reasons for suggesting Rogue.