The idea has merit when perhaps it is localized in certain areas of a given ski resort.. ie, the bunny hill, or for zones already designated as 'slow'. That being said, if ski resorts become overzealous and institute these sorts of regulations all over the place, you can bet there will be a backlash from the experienced skiers and snowboarders, for obvious reasons.
I know if I had, say, children under 10 skiing around on learners runs, I'd appreciate it if park rats weren't bombing switch around them, and similarly, if racers weren't sending it on these runs. Thats where I feel a speed limit would perhaps be appropriate.
On the other hand, I don't think there's a place for radar guns and monetary penalties for shredding fast around the majority of a given mountain's runs.