this was an interesting article. i don't know if i fully side with what this guy says, but he does make some points.
personally, i feel an 80 hour game gives you plenty o' bang for your buck. but what is too short of a game? 40 hours? 20 hours? should pricing be based on how long you might play it?
anyway, it's not a super in depth article, but still interesting.
That VideoGame Blog » People “tired of 80-hour games,” Winterbottom dev believes