Shadow of the Colossus is hardly over 8 hours and its the greatest game ever
Its better to be great and short rather than long and repetitive (Damn you Curse of Darkness!!!)
Aha, but it's also better to be "great and long" than "great and short", though yeah, "great and short" IS better than "long and repetitive" or even "short and repetitive"(which is probably the worst of all).
As for the dificulty, yes, it's being aimed towards casual players, meaning that hardcore difficulty will be sacrificed so it could be, overall, a more user friendly game. Casual gamers aren't ones to invest long hours in game. They want something to entertain their for what ever short period(hour or so) they are playing AND they want to get through the game with the at a moderate rate and not face as much challenges as possible(because that will make the gameplay experience more unbalanced as far as game play time is concerned). That being said, a casual CV game isn't a bad thing. A lot of the more recent CV games(IGA ones) were more casual, as well.