For a single player experience I think it is a bad design - having companions be “player’s equal” creates narrative issues. And while Bioware’s “chosen one the leader” trope got pretty stale throughout the years, so far Larian’s approach with vague protagonist didn’t work for me so far (mainly D:OS2. I am judging BG3 via gameplay videos due to my hardware limitations).
For coop though, it’s brilliant. Companions being playable means coop players can drop in&out.