Decoupling behavioral expectations from physical appearance would be great! But that would be a titanic task, and shouldn't fall solely onto trans people, whose mental health often depends on seeing oneself as and being seen as the gender they identify as.

In addition, there is an undercurrent here that suggests "changing your body is bad," or perhaps some appeal to nature. If you hold these ideas, I would like to ask why, and perhaps reexamine why you believe so.