I wouldn't say Visual/Oshare Kei is a music genre, but the fashion bands wear helps define them in that genre. I think the 'Kei' titles are getting placed a lot more as a music genre, due to the fact, by hearing it, you can usually tell the style of the music. E.g. An Cafe is Oshare Kei, so you think of colourful clothes, and a happy pop-rock kind of tune. the GazettE is Visual Kei makes you think of dark clothes and hard riffs, with dark lyrics too. Sometimes it helps when a band has 2 genres, E.g. Visual Kei/ Hard Rock. It gives people a better idea.
I like it too. Its funny that he suits so many styles. This ones kind of like Dark Miku. lol