People leaving is the only way it will create a noticeable reaction to CRZ issues.
Posting on the forums is good but loss of subs is more apparent to Blizzard than words in a forum.
There are not many ways a community can change things like CRZ without using their wallet, a loss of players may seem funny to people who havent noticed how the CRZ is affecting certain realms and activities but quitting and removing your sub is the only way to get Blizzard to take notice of this.
I wouldnt mind CRZ if it was for certain named zones but all zones barring Faction Capitals are effected. I am on a PVE Normal realm and see that the impact of more people and less herb/ore nodes is going to create economy problems.
The CRZ issues will become more apparent as the new chars being created in MoP start to leave the starting zones. You will notice that the majority of people who like the CRZ at the moment are mostly 85's who are geared up but its those who are not that will be the worst off. Of course Panderia and the panda start zone are exempt from CRZ at the moment.
As people start to level their new Pandas and try to level their mining/herbing then CRZ will become more apparent. I personally have stopped going out to herb or mine or skin for the past few days as CRZ is hard to work with.
Personally i would limit CRZ to Outland only for a few months to test its impact on how people interact and let the Old world ( Eastern Kingdoms / Kalimdor ) be CRZ free along with the Cata level 80-85 zones. Just dumping CRZ on everything has just made things awkward for many people to get prepared for MoP.