Some people actually rotate directional tires by dismounting them and remounting them on the other wheel. Kind of not very cost-effective on a tire that wears down as fast as these do though, eh?
It's also been noted that the "directional" part of directional tires really just refers to how the tread responds in the wet, and how quiet the tires are. I've known a lot of racers that rotate their directional race tires--they're running enough camber/toe to get the inside edge to wear out rather fast, plus their running shaved R-compounds where hell, the tread is just slowing you down.
But, that's a very specific application and you didn't hear it from me!