Yeah, and why are most of the Mah Jongg games themed around underage cartoon girls whose clothes tend to fall off? Is this some cultural thing I just can't grasp until I've lived in Japan?
Personally I think the MAME guys need to build different versions according to game categories. Here's a couple to start:
MAME Japanese soft porn puzzle games build 0.66
MAME Vertical shoot'em'ups with loud snare drum music build 0.66
MAME Fighting games from Asia not quite as good as Street Fighter build 0.66
Take those three category games out and the remaining MAME ROM set would fit on one CD no problem!