This might be simplifying the issue - I'm sure I'll be put straight if I'm getting this wrong but I think the problem was that if you were a TS seeking hormone treatment and eventually SRS, you had to convince doctors that you really 'knew' that you were female (that's not putting it very well but I hope you can see what I mean). So if they suspected that you didn't regard your penis with horror and, even worse, might enjoy using it now and again they considered that you were merely some kind of fetishist and would refuse treatment. I say was but this may well still be the case...