That's probably the only thing that bothers me for the moment in the game. I just finished my second run with Shadowheart, Astarion, Gale, and myself as another wizard. Cause i need someone to talk about magic in my groupe and Will is kinda thick in this matter. It's playable, and i think my next run where i'll play a warlock and be the only profan caster in the groupe will be playable too... So Larian/DnD5e made a good job at making groups of 3-4 playable. But i can't imagine i will ever recruit in my group something like a ranger, a sorcerer, a bard, a druid, a monk... And it's sad.
Just throw at me twice the numbers of gobelins and let fights last another hour, i don't care, because you made a great game and it's fun to meet your characters and lead them into battle, learning how they interact <3