People are just antsy, I suspect. Earliest impressions of a game are always put forth by advertisers, who probably think we'd all want to buy a game for its sweet pre-order bonuses and internet celebrity cameos. It's when the "slightly less early but before I'll get a chance to play it" impressions come in from Gerstmann and co that I'll start to pay attention.
Though I suspect I'll ignore everything and pick it up on the first day. I'm a predictable sort.
/edit: Oh hell, that was a bit of a necro bump. My apologies, G-numbers. Maybe move the discussion over to how expectations shifted after this demo?