Lae'zel is fine, for what and who she is. And you're never going to be friends with all your companions at the same time in the same playthrough - that's part of the game.
There is nuance, or at least the beginnings of it, and I believe once we are able to go to the Gith Creche her story will really start to unfold. (And her mental state will probably start to unravel!)
It's possible but it's really hard.
