The only reason to rocker your park skis would be if you keep getting too much pop and fly out of the ozone, then I guess it would be ok. But other than that every other reason is dumb. You can't control the skis on the snow, you can't get any pop off jumps, and theres no support on landings. I have Hellbents, and Pipe Cleaners. Pretty much opposite skis, Hellbents are rockered, Pipe Cleaners have insane amounts of camber. Pipe Cleaners get a shit load of pop ollieing, poping off jumps, popping out of butters, pretty much better in every way. The only reason I like the Heellbent's rocker is because it makes it easier to keep your tips up in powder. They suck in the park. Rockered skis doesn't make butters easier! Ass! that's getting annoying. You need to be able to POP out of butters so you can do 3s and 5s and shit. Not just have floppy skis so you can get on the noses......then lay the tails down and go switch out....
Park skiing is about popping. Keep your skis the way they're made.