So long as the semantics does not stop good people suffering then it shouldn't be an issue.
I feel nervous labelling anything in case someone gets pissy, but this is my personal take at this stage.
I personally see being transgender as a physical birth defect not a mental disorder.
As a 46XY I was 'supposed' to be a boy, but one of the two hormones that communicates this failed at a critical stage in development (e for me as an mtf) and as such my brain development did not get the message and developed in that stage stayed in the default female state. Thus my brain, or at least a core part of it, is expecting to be female though my body male. This mismatch creates stress, depression, anxiety and a range of complications which I bundle up as Gender Dysphoria. No amount of therapy can remove this mismatch as it is physical, but aligning body to brain eases the discomfort and gives stability. Therefore is is not a disorder of the mind. The mind *is* right- in me it is set up to be female.
Therefore I see GD as an illness resulting from that birth defect that effects the mind, not a mental illness.
I feel a bit like a mutant in the x-men. Only without the cool powers. Evolution means we are in flux, tiny changes 'mistakes', mutations, variations... humans are not a pure ideal thing, but a whole range of beings different but compatible. I am neither male or female, I am my own specific mix based on the billions upon billions of random things leading up to my birth. That little change that sent my brain one direction, my body another- call it what you will- disease, abomination, curse, karma, mutation, variance, two-spirit... it doesnt matter- so long as I am recognized as having human rights and am not barred from doing the thing I need to live a safe, happy life as part of my community. For me, HRT and surgery a must have to exist in peace. I would like that recognized by the medical and medical insurance systems.
But you know, super powers would have been nice.