Mass Effect 3, Dragon Age 2, Skyrim, Dead Space 3........
Just 4 games amongst many which I can think of that are way below the standard set by their predecessors, but are also - IMO - poor/average games in there own right. Yet the hype and praise that surrounds them is massive.
Now that's based on only my opinion of the games, and some may think they are great instead. However, I would say it's fairly undeniable (although fair play if you wish to debate it) that all such games aren't anywhere near as good as the general consensus would have you believe (if not now, then on initial release), and that none of those games will be on a "greatest games" list in 5-10 years time, where as the initial and in some cases current praise leads you to believe they will be.
Essentially, how are so many games which don't hit the spot being lorded so highly, both on initial release and so many months after?