I do believe that most TG people have what I would call a "disorder." The problem is that their identity, who they feel themselves to be, does not match their genitalia. What I don't understand is why some people insist that in this situation it must be the inner identity that is "wrong" and these people should somehow force their minds to conform to the gender reflected in their genitalia. To me, it makes so much more sense in most cases to fix the part that is actually fixable by transforming the genitalia and hormones to match the identity.
I do think there are some exceptions. My cousin, for example, is transgender female to male. I think she is transgendered not because she was truly a boy born in a girl's body, but because her parents royally screwed her up psychologically. In her case, and maybe others like her, I think counseling would have been much more beneficial to her than surgery/hormone therapy and eventually resulted in a much healthier, happier person. But I think he is in the minority. And even though I think he made an unfortunate choice, I honor the fact that he now chooses to be a man, I call him by his preferred name, etc.