One thing, as someone else mentioned, they really nerfed Intelligence. Which rubbed me the wrong way. It used to be that Intelligence gave all characters skill points per level, so it was useful for anybody to have more intelligence. Now, it’s basically useless unless you need it for a specific class and only the wizard needs a high intelligence value. It’s close to the best dump stat. I suppose in early editions of D&D it was pretty useless if you weren’t a wizard - but at least the wizard was the master of arcane magic and so intelligence had that association. Now Charisma is the most common casting attribute and it is also valuable for more skills than Intelligence too.
I’m also not crazy about how they do saving throws in 5th edition, but that is a bit of a tangent.
I can understand thinking of the warlock as making deals with entities and so gaining power that way, and I don’t necessarily object to that idea, but personally I see a warlock as more of an intelligence based caster - someone who looks up dark rituals and uses their intelligence and knowledge to make their dark pacts. That is why I was thinking that letting the player decide would be good.
I think that Charisma Baer clerics actually make sense. Because the cleric represents the deity and should be able to carry the message of the religion to the people. I also see a representative of a deity as having a holy aura or presence about them, literally being in the presence of a saint, and so that could go along with Charisma as a casting attribute. Then the cleric and paladin, thematically connected classes, both use Charisma.
I could certainly see a good case for Constitution as the casting attribute for sorcerers. I’m not sure how balanced that would be, but I don’t think it would be that bad. If it were a mental attribute, I would personally say Wisdom makes more sense.
I can’t yet feel comfortable with all of the things that newer editions are saying that Charisma has. Like force of personality, as though personality involved some kind of literal force, or an ability to impose one’s will on the universe. It seems like a stretch to me. For casting classes that use Charisma, I would like to have some reason why being likable enhances that magic or why having magic of that kind makes you more likable.