Rewards lead to exploiting to get those rewards...two words:
Trading between random people who don't know eachother and trading between friends and guilds.
For this one simple reason rewards should not be implemented. It ruins games, just look at SWTOR open pvp (not that it didnt suck in the first place, but a cake always needs icing.)
People cheat and exploit, always have, always will. Do not make rewards!
I think the reward should be dropping crystals instead of destroying them. You can lose the crystals anyhow so its no more loss than is already implemented. Also it can't be exploited.
you didn't specify what kinds of rewards. if people received a bit of gold for each kill, you could place diminishing returns for each kill. rewards can be done correctly, and incorrectly.
In followup to Alia, rewards within one's level range could be a good incentive, assuming 'done correctly'.
Small rewards such as dropping the crystal not destroying it and little amounts of gold would be okay, but what kind of incentive would that be? None.
People want a 'reason' to go pking...rewards 'worth that reason' would need to be bigger than just a crystal or few thousand gold. Something like that just would not work.
I agree with those who think rewards can be done correctly. If trading kills got to be a problem they could implement a rule that the rewards decrease with each kill of player X killing player Y within a given time frame. Easily done and will help game in long run. Lack of rewards leads to boredom leads to cancelled subscription.
PvP is about: FIGHTING OVER THINGS.
PvP is not about: MEANINGLESS BATTLEGROUND GEAR POINT GRINDING THAT IS RESET /TREADMILL EVERY PATCH.
Example of quality PvP: A rare BAM with excellent drops spawns in a FFA PvP area.
Example of horrible PvP: Kills in the open world or within a battleground award points which can be used to purchase PvP-specific gear.