That's not the Olympics that makes that rule, it's snowboarder's preference. You'll notice that they all perform at least one standard maneuver in pro events like XGames too.
They simply view a pipe run differently than skiers. Where skiers are more concerned with a pure trickfest, snowboarders consider a standard trick to be a critical element in a well-rounded run.
The viewpoint they have, is that a run without a standard maneuver is lacking a very important aspect of the sport. It just shows that boarders still have more of a skate/surf mentality...
Personally I like it, it ensures that style is still super important, and it looks sick to see a super stylish straight air in the middle of a run that is otherwise tech as hell.
The way ski pipe is going, soon you will never see a run with less than at least 720 every single hit, and I think that's taking away some really impressive shit from the equation (think Laurents alley-oop first hit in 06 winter X).
Anyways, I realize that's a litle off topic. Of course ski pipe should be in the Olympics! FIS is fucking retarded that they haven't already submitted it for Vancouver, because the IOC would likely be more than willing to accept it.