To elaborate a bit on what Squilliam said, FMVs are the main culprit of multi-disc and massive games. Let's take FFXIII as an example, most of the space used on the Bluray are what? Uncompressed FMVs. I've always (since the PS1 era) thought that FMVs are a waste of space and development time, and I thought they would be finally ditched this generation thanks to the real time graphics achieved by consoles... but here comes the Bluray with it's massive space and helps even more to spread their usage. This also applies for audio; I'd prefer to see developers working on new and innovative compression technology that matches uncompressed, instead of them going happy-go-lucky with uncompressed stuff.
Procedural generation, the programming technique that generates stuff randomly from code rather than having assets, has been around for many years, but I'm not sure it's widely supported. Actually, I can't immediately recall any game using it for something, maybe someone can refresh my memory. Perhaps it's harder to implement on games, needing more work or something, and that's why it's not used.
Also, I think the PS2 lacked any type of texture compression on hardware... because I'm sure the Xbox and GC had S3TC on hardware, which gave them a huge edge back in the day.
Today it's been a nerdy day for me hehe...
