It's for the folks that are competing in USPSA competitions. They will use the heavy brass grips, brass gun mounted "flashlights", etc... to make the gun heavier to help reduce muzzle flip. In some cases these bolt on devices do help folks manage recoil but not everyone will benefit from the increase in gun weight.
I'd argue that CZ's in 9mm are already very easy to shoot and manage recoil due to their all steel frames, low bore axis, and superb ergonomics. If you have decent grip strength those bolt on weight additions will only slow down your transitions and not help your splits.
I don't know why they cost so much, I imagine it has to do with material cost and machining cost vs polymer options. If they are deemed a competitive advantage they could be capitalizing on that and value pricing them to competitive shooters.
Cheers,
Toby