Eh, it's not as terrible as it could have been. I'm wondering if this was written before AWE, when we find out who Tia Dalma actually is.

Because said co-stars dare to try to be attractive and likable while Depp is in front of the camera.

Exactly. I never got the feeling that he was constantly calculating every single line. In his conversation with Will here, for example, my impression was that his thought process was "Okay, gotta see Tia Dalma, this dude's annoying me, hmm, he could work to help with this plan, I'll sucker him into it".