interview with Silicon Knights president Denis Dyack up on their site. In it, he says "Legacy of Kain had about sixty hours of play, but games have changed. People don't want that any more. I don't care how good the game is, I don't want to play something that's one hundred hours long."
He goes on to argue that games not only need to be shorter, but need to be split up into chunks so that the masses can digest them easier. He also points out that the games need to be self-contained. "That was flaw in the The Lord of the Rings movies. Too Human will be self-contained across each game of the trilogy."