Game marketing rule #1, when you are releasing an exclusive game to a platform hype it as "<game> can only be done on <platform> because of <unique feature>" ...
Disc size was a huge issue when you were talking about the difference between an 8MB N64 cartridge as compared to a 640MB Playstation CD and consumers wanted FMV and CD audio ... When you have a system with the processing power to provide high-quality real time cinematics and you can handle highly compressed data going beyond 9GB is foolish and 18GB is moronic ...