Or is it just easier to hate?
This.
In the playoffs there is always a bunch of 2nd. and (especially) 3rd. line guys that ramp it up. I think it has to do with two things: first you can increase intensity but you cannot neccessarily increase skill. Really, I don't think the Sedin's can increase the "intensity" with which they cycle. The playoffs demand that teams tighten up defensively, and that is going to have a negative on impact players that thrive by slowing the game down.
Secondly, teams demand that their best players carry them for 82 games, with top forwards spending 20+ minutes per game (I know, the Sedins average only 18+ minutes per game but it is still more than the 3rd. and 4th. line) means that at the end of the season they probably don't have as much left in the tank as the players on the roster that only get 8- 10 minutes of ice time.
Guys like Crosby, Toews and Kesler are the exception not the rule.