Some have wondered whether it is really slash or if it is in fact gen. The definitions of slash and gen have been growing and changing since they were first uttered. Some people consider a story with no explicit sex of any sort to be gen, whether or not the main characters are gay or straight. Some consider a story gen only if there is absolutely no homosexuals of any shape or form in it at all. Or you could say that gen is anything that the regular viewing audience of the show could expect to see on the show.
Definitions are a bitch that way, changing and evolving without anyone being able to control it.
I consider QAF and VG to be slash for two reasons. One, they involve same-sex relationships and two, the world that the shows are set in are still predominantly heterosexual. For me that means they are slash. Feel free to disagree, but that's where I stand on the labeling issue. There is another aspect of this fandom that bears mentioning.