1. The damn pet... Please just remove the energy cost of gnaw and leap. The pros macro claw to either DC or SS, but it's a lot of work to make the macros, use them correctly, and manage pet energy while staying on target.
2. Chains messes with our rotation/GCD. Frost get a free aoe snare (yes, I know you need chillblains, but its pretty standard for frost).
If they could make blood plague function as a PASSIVE snare (not multi target, you would have to use unholy blight or pest. to apply it to multi targets) and remove the energy cost of pets, You would see a much higher player base as UH in PvP.