Barbarian Gale talking about reading books and petting his cat in a tower here I come!
Joking aside, I don't mind one bit. It's optional and some characters aren't really tied to their class anyway. Astarion for example could be anything except maybe cleric or druid...? I can even see him work well as a vengeance paladin to be honest, especially if you play him as an origin character who wants to take revenge on Cazador. Lae'zel I think works well with all martial classes. She would be sick as a monk imho. Same thing for Karlach, but why not make her a magic class specialized in fire spells? That could also be cool. Minthara can be any class, really...