And I'm sure they didn't cut content. They probably just have better compression than they used to so they can fit more in less space.
I am not trying to target you specifically as others made similar claims, but that's the way it's always been. Stuff always gets cut because of space constraints. Blu-ray would certainly minimize that, but I'm sure many PC users don't have one for their computer, and obviously the 360 would be right out. When you honestly examine everything, the 360 is the most limiting factor of all three platforms. I'm a 360 fan, but I can admit that.
And to say that there's no way to make a game like Skyrim for multiple discs: there are other games with open exploration that span multiple discs. Don't ask me how they do it, because I don't know; all I know is that they somehow accomplished it. The only thing I can logically conclude is that it's a cost consideration. That makes sense to an extent, especially if they were only going to need 10% of a second disc for the rest of the content. It would be cheaper to just hack off enough to fit it all onto one disc.
Also don't forget, logically there must be even more room still available on the 360 disc, because eventually there will be a GOTY edition with the expansions tacked on as well, and they obviously aren't going to cut out even more to fit those on there. Thus, there must be some room still on the initial disc.