Zeraph

It's all about perspective, some people grind for equipment because they find it fun (to aquire, to get, to use, or whatever), but others only grind for it because they want to be able to compete and have a fair chance at PvP. For the first group the level cap will be a good thing because they will have more game to play, for the second group it will be bad because it's just one more time sink until they can play freely again.

This conflict comes about because the two modes of gameplay are intertwined (PvE and PvP). A real life example would be paintball, some players who have lots of money can afford automatics...with a little skill these players can dominate players who have less accurate and crappy rate of fire guns. If you don't know anything about paintball just think of fighting a war with muskets versus machine guns. For paintball players who just want a fair competitive match, it's bad news when some new expensive toy is invented/put on the market, but good news for those who just like cool equipment and/or can afford it.

Just like in paintball, not everyone in WoW can "afford" (either through time or fun factor) more grinding/raiding more for levels/equipment.