Disc space used to matter, but it really doesn't anymore. Putting games on multiple DVDs works just fine for 99% of games; if you really have a problem swapping discs every 10-20 hours of playtime, then you really need something more important to complain about. The only games that really don't work well on multiple discs are sandbox games, but those are few and far between, and then only when the data can't fit on a single DVD is it a problem.
HD-DVD/Blu-Ray just aren't a significant jump from normal DVDs. Developers can now cram a metric ton of compressed textures, audio, and video on to a single DVD, and the fact that those things are compressed doesn't matter to 99% of users. It won't be until the next generation when the market will be ready to adopt a next-gen optical storage format - that being, when it's cheap enough that it doesn't make your console cost $600 at launch. :)
"'Casual games' are something the 'Game Industry' invented to explain away the Wii success instead of actually listening or looking at what Nintendo did. There is no 'casual strategy' from Nintendo. 'Accessible strategy', yes, but ‘casual gamers’ is just the 'Game Industry''s polite way of saying what they feel: 'retarded gamers'."
-Sean Malstrom
