Really, who cares if they can fit all the games on one disc, its not that hard to change discs, and its cheaper to release the games on three dvds instead of one blue ray or HD-DVD.
I think blueray/hd-dvd is the biggest smoke screen since the CD vs. cart debate. Most games dont fill up DVDs, let alone HD-DVDs. Remember when Sony said the 64 would suck ass because it used carts compared to the "far superior" CD? The 64 was better than the PS1 on every level relating to the cart vs. CD debate.
I think blue ray is a big mistake for Sony, it will hike the price up a lot, heat the system, and really give little in return. Sure it will be cool to play blueray on my PS3, but id rather just get a stand alone player and buy a cheaper non-blue ray PS3.