Almost every PvPer with beta seems to agree from what I've read so far. You'll hear various classes are overpowered and there's argument, but they all agree dispels are broken.
I think most PvPers without beta can just imagine dispels in a no-dispel protection environment, does it not seem like they'll be completely ridiculous if no changes are made?
Can you imagine a double dispel team in Cata now that Druids and Shaman have defensive dispel? SPriests also keeping their dispel means they don't have to necessarily run double healer either.
Can you imagine trying to heal as a druid or priest vs. teams with offensive dispels still removing 2 buffs per cast when all your dispel protection is now gone? What about vs. 2x offensive dispels?
It seems to me like this going to be a major problem and isn't getting enough attention.