I would like Shadowheart to focus on heals, while still keeping her trickery god related parts during the story (would be too much asking a complete re-write of her story), but not during fights.
As well with Lae'zel to have a different build, all the details we pick for our own custom character, except looks. Same with the others.
The main reason for using the default companions is their involvement in the story. As well their unique looks, voices and everything else; and these would be all lost if we just replace them with a silent, custom character.
The game is in early access right now but I believe we might be able to do that once the Early Access ends. Larian did say that when you start a game you will also be able to either create your own character or choose one of the companions as a main character once the full game is released.
