I like the idea of event PVP. They're interesting and challenging. But in the present Goblin event, the rewards need some re-thinking. Why would I try to win four raids with X character who may cause me to go in with a less-than-optimal team just to try to win two tokens for X character? I don't have Bramble, so I'm jeopardizing my PVP standing for a reward I could get in 30 seconds with two loot keys. And I can't complete the Bramble PVP quest because I don't have Bramble.
My suggestion for the future: make the rewards worth the risk. Get a token for each of the first three raids won then two for the last. Or do a 1/1/2/3 progression for a total of six possible tokens. And offer tokens not easily obtained elsewhere. I don't mind playing to win tokens, but not for such a low return. Win a raid with a goblin on the team, get a Bramble token. Win a raid with an all-blue team, get a Kai token. Win a raid with an undead team member, get a Zomm token. Make these things worth doing. That's what keeps us playing.