While those do need to have a say, the issue is a bit more complex than that. Anyone with some basic understanding of trans activism should be aware of the reality trans folks face in that area: it being considered a disorder can be beneficial to them as it opens the possibility of state financed (or otherwise cost-lessened) treatment (access to professionals, to counseling, to HRT, to surgery...).
I'm more inclined to letting professionals do their thing but, as it is, the decision is more political than it appears on the surface. And it's not something trans folks themselves agree on.