I disagree. Map backgrounds are the choice of the mapper, and should (if done properly) reflect how the mapper feels about that song. Using a default background would defeat the purpose of relating the background to the song (psychology).
This needs to happen. If I intend to ever play this game in a public place I do not want anime women invading my screen on map selection!Don't download maps that are subject to those backgrounds (i.e. TV Size, "kawaii" anime).