A good point and I would think that there's definitely going to be a lot of games there. Not all games are fully emulated by MAME however and so if a game does

A good point and I would think that there's definitely going to be a lot of games there. Not all games are fully emulated by MAME however and so if a game does not have sounds emulated correctly then often .WAV files will be included of the sound effects and these will be played instead of actually emulating the sound chips. These WAV files can actually be pretty huge as people want to be as close to the original sounds as possible. Things like Dragons Lair (basically a large movie on a Laser Disk that requires you to do quick-time events to keep watching the movie) will probably also be adding a lot to the size.