Well, it was Microsoft (including guys like Spencer) and insiders hyping it up.
If they wouldn't act as if people will see stuff people won't believe then people wouldn't expect that much.
But with all this talk before E3 you just had to believe to see awesome Gears story scenes, some big surprises (nothing was really big) and so on...
Without all of this I guess most wouldn't have expected anything special
Yeah, insiders really dropped the ball with this one, remind me never to trust a word they say again when it comes to hyping something up