Late to the party but...gender fluidity is trendy, and also it's as real as any other label. I've softly identified as gender non-conforming since I first learned about it about 10 years ago and felt that it best explained a certain discomfort I had with being seen or labelled as a woman. Yet I had no desire to transition or try to pass as a man. I personally don't like groups or give a crap about trends and I'm not even terribly public about my gender, so this isn't about social capital.

I honestly don't know how transgender is so much more legible to people than gender neutral categories. Both involve a feeling of disconnection with a gendered label and that doesn't always manifest in the same way. Even trans* people are not a monolith. And "other" gender categories have existed in other cultures for a long time such as the native american two-spirit which may be hundreds of years old. Also the category of "gay" as we know it today is fairly modern although homosexual activities and inclinations go way back. So if we all sign on for gay and for transgender--why not gender fluid? It may be trendy but if more people are exploring different ideas around gender or ways of relating to gender--good on them! We'll all be dirt soon anyway.