I disagree with your interpretation of the study, Sqad -- indeed, so far as I could tell, so do the authors, who it seems to me were saying that the GRS operation was not in itself inadequate but couldn't be seen as an answer in isolation, ie that better care was needed before and after any such operation. The higher incidence of suicide was compared not with pre-op transpeople but with the population as a whole. I don't see that this is a valid control group to draw the conclusion that the operation is un-necessary or counterproductive.
In reality I don't think you can say either way, at the moment, as the world isn't really trans-friendly enough. For some trans* people, though, aligning their body with their perceived gender does make a significant positive difference -- and such people shouldn't be restricted from having an operation that can improve their well-being for want of cash. As long as the procedure for assessing the need for such operations remains fairly stringent (ie that a patient has been properly assessed before being operated on) the operation should continue to be available on the NHS.
The most important thing, though, is that we don't define transgender care solely by a single operation. Again, the over-riding message from this study is that the entirety of care needs improving, from counselling and support all the way through to aftercare. Perhaps because the operation is so iconic it has received more focus (from both sides of the debate) than it should have.