I feel that it is definitely becoming a fad. However, I am speaking as a non-binary and with that, God, is the fad even worse than with FTM in many ways. It's very frustrating because it undermines people who actually are. I can understand exploring your gender, that's fine, but all the angst and how they over react to issues that they don't even really face... It's making most of the people trying to be trans* allies tired of dealing with them, and to a point making non-binary as a whole appear to be an adolescent phase. ( I suppose, they think male and female are only extreme points; and since they don't meet either point, great Scott, they must be genderqueer.)
In addition, it makes it very hard to find other people, who I can actually relate to, and in some ways, makes me wish even more that I could just stop being non-binary, because their abuse of the term is making me feel like some sort of joke. Hell, right now I'm not even sure if being genderqueer isn't just a stupid adolescent phase, and there really is no comfortable place for me, but I should just suck it up and try to pick a side (and from there it will settle out). But you can't talk sense to these people, because what can you say without "violating their gender identity?" I don't think they grasp the difference between wanting to be a certain gender and actually being that gender. Also, its fine to sometimes present as "gender->-bleeped-<-" or androgynous (gender->-bleeped-<- and androgynous are popular right now) and still be cis. It's also fine to be gender-questioning; just don't throw a bloody parade about it. (Even on the internet, deary)
Hell, they'd probably even argue the same points I am without even realize their being hypocritical. Hell, maybe I'm just a hypocrite and the jokes on me. I felt so relieved when, I first came across the term. Now, I feel like a fool, but after getting hope; it's hard to go back my previous line of thinking (casually ignoring that gender exists more than a pronoun here and there as best as possible).
Ah, my apologies for the venting and possibly offensive tangent. The last bit below might be useful though.
Part of the reason this is so widespread with FAAB's might be partially because of a common medical disease known as PCOS (said to affect one in five "women"), which has gender confusion as one of the effects. However, once on treatment (which can sometimes be as simple as birth control, sometimes a bit more.) most people go back to feeling more comfortable as female.