VLC Installer should have an option called "Associate only with unassociated file types" (aka those file types no other media player currently installed in your system recognizes).
For example, I 've met many people who accidentally made VLC their default software for music playback, although they might prefer some other player for music playback, and they 'll have to re-associate all the music file types with the other player.
How easy is such an option to implement?