Honestly, a theme doesn't have to "inspire" in order for you to be able to explore new game mechanics, or even make something interesting. It is there as a guideline, a limitation in order to bring about real creativity. On top of that, having a prompt to bounce off of helps focus each developer into making something within the short amount of time given. Even the theme "minimalism" could bring about all sorts of interesting games if you give it enough thought. (heck, you could basically do anything you want under that, if you define the theme to mean minimalistic graphics/abstract representations of something in a minimal way. or even minimalistic mechanics that allow for complex puzzles/levels. look a VVVVVV, that could EASILY be a candidate for the minimalism theme, and is a widely popular and acclaimed game)