I don't understand the hate either.
The majority of the complaints don't seem to be about the feature itself but about having more people around. If there were more people on all the servers you would still have most of the same "issues".
For example mob tagging is not a CRZ issue. Mob tagging has always worked the way it does currently so you can't blame it on CRZ. A rare pet is called rare for a reason.
I see no issues with materials on the AH either. Some prices may be high but they aren't high because of CRZ but because people at level max simply make more than enough money to pay a higher price than they would have in the past. I am leveling up an alt myself and thanks to the inflated prices on AH I am able to make money faster than ever. And that is with level 90s in my leveling zone, which again has got little to do with CRZ because if my server would have been more crowded they would still be around.