There's an issue in Dungeons and Dragons, and it's one I'd hope that Baldur's Gate 3 doesn't follow. It's the fact that fighters don't really do anything except hit things. This isn't so bad in a tabletop experience, where you have a DM who can give the fighter things more interesting than being the 'combat guy' but a CRPG is going to potentially run into issues.
Think of it this way. Fighters are there for combat, and they're really only there for combat. Maybe they can help out on Strength checks in dialogue, but I'm yet to encounter any. For the vast majority I've seen, the dialogue checks are Charisma-based, with some Intelligence and Wisdom ones. If you pick a fighter, you get to be good at combat, but if you want to potentially be good at any checks that come up over the course of your adventure, you need to take points away from your niche and put them into, say, Charisma.
Compare this to any of the classes like Cleric, Mage, Warlock - their statistics do far more than Strength does. Not only do they grant increased combat ability, but they also grant increased roleplaying opportunities. They also add to way more skill checks. If we assume a Fighter is going to go heavy on Strength and Constitution, they get exactly one skill that enjoys the benefits - Athletics. If I want to have a shot at some of these checks that come up, then I need to put stats into skills I don't otherwise use. Say, for example, Charisma. And all this does is make my Fighter worse at the thing he's supposed to be good at - combat.
I imagine people will say that it's the price you pay for picking Fighter, you're the combat guy. But let's not pretend that picking any of the other classes will mean you can't prevail in just about every combat encounter you'll have over the course of a CRPG. I doubt there'll be many encounters where having a fighter will make the difference between life and death. In fact, I'll suggest that there'll be many encounters where you'd prefer having one more spellcaster, given the number of things they bring to table beyond 'use sword on enemy.' I imagine people will say that's just how it is in DnD as well, but this isn't a faithful adaptation and, ideally, I'd suggest all classes be somewhat equivalent. As it is, when you pick Fighter you get to use a lot of weapons and armor - at the price of being sub-optimal at anything outside of combat.
it wasn't so much an issue in DOS:2, because you could pick and choose your skills as you wished. The class-based system will not change, I imagine, but it's really making Fighter to be a bad choice for a player who might be interested in anything beyond combat. Ranger, for example, is probably better in all circumstances. It's exacerbated by the limited party size, too. It'll be made even worse if the spellcasting classes get opportunities to cast spells during dialogue. Like, it's a little bit silly that Charisma controls Persuasion and Intimidation, isn't it? Deception, too! I think you could make a case that Strength could bolster Intimidation, for example.
At this point, Fighters need something to make them feel like they're a real choice for a player character, and not a trap choice.