I'm not really a fan of PvP in general but I prefer real time PvP rather than turn based where you have time to decide on a move
I think PvP should exist is more RPGs ... but it should be optional of course, and shouldn't really impact the PvM side of things ...
I personally have never cared about PvP. I'm not that much of a hard core MMO or MMORPG player. I'm normally bad at PvP anyways.
I think that is best part of mmorpgs, that is where u show up your skill,tactics,rotations unlike PVE where you just press one button