Visual Kei is a sub-genre of Japanese Music that focuses on self-expression, most Visual Kei, bands do not sound the same, as that statement could be used for Rap as well, but Rap fan will argue that it takes an ear, same applies to Visual Kei. The Key of Visual Kei is too express a message and bring a twist on it. Not all of VK fans are female and only care about looks. The GazettE, one particular VK band has amazingly metaphorical lyrics (if translated). But like all band VK bands talk about a multitude of different themes and should not be dissed as such. Also the 'cross-dressing' comes from their culture which performed (and still does) Kabuki, a form of theatre where all actors are male, and so if the bands theme requires females, cross-dressing occurs. An example of this is Versailles -Philharmonic Quintet- whose theme revolves around two waring noble clan set in pre-revolutionary France, with a style similar to speed-metal.
Visual Kei is just another form of music which doesn't want to conform to popular music, like metal