The reason anti-gay rights advocates like to use "homosexual" is because it evokes being gay as a clinical condition -- which makes it easier for people like Colorado Republican Senate candidate Ken Buck to compare being gay to alcoholism. For them it's a disease, it's a disorder, and so it must be referred to in scientific-sounding language. Communities reappropriating slurs against them is probably as old as the use of language as a tool for oppression, but that doesn't actually happen if the term is actually "neutral" as we use it in contemporary language, not as it is itself defined.
That's so gay. Would you say the same for "heterosexual"? That sounds just as clinical. Most of the time I use "gay". Maybe we can all agree that the only thing no one should ever write or say is "LGBT". It looks and sounds like a place in Bosnia.