The problem isn’t WXP. The problem is the underlying mechanics of the game. (No healers, no trinity, downed state, 5-man limit to AoE etc.).
That is what creates the zerg. The rewards (like WXP) just amplify the underlying problem.
Solution? ESO.
I fully agree that the mechanics of the game are what support the current zerg play but I don’t think healers/trinity, downed state, or AOE limit contribute to it much. An increase in AOE limit will just make zerg vs zerg fights that much faster as the side with more AOE’s will win. It is a double edged sword, it might allow a small group to take out bigger groups but it also allows much bigger zergs to take out big zergs.
I see a few big issues that are supporting the zerg lifestyle. First there is no friendly collision detection, this is a huge negative that could easily keep people from running ikittenerg. The lack of character models blocking LOS, add this and watch as people spread out so their damage isn’t blocked. The keeps, towers, and even camps are way too easy to capture. It should take the better part of a day trebbing a wall to knock it down, but currently set up 3-4 trebs and you’re in within 15mins. The whole supply system allows people to just stop in, pick up supply, and leave without caring if it gets capped because they will just recap it when they need supply again. Make supply trickle in but allow players to pick it up(each player can carry 1 supply) at camps and deliver it to keeps/tower. The effect will be 3 fold, siege will be harder to build so it will need to be defended while being built, camps will need to be defended in order to continue getting a trickle of supply, and people will need to constantly run supply. That splits the zergs into defending siege, defending camp(s), and running supply.
In order to make zergs break apart you need to give them multiple objectives(best case) or negatives(worst case). GW2 just doesn’t do either and thus we have zergs running around.
As for ESO, that’s honestly not going to be a whole lot better. They already have a giant design hurdle in their alliance system. One alliance is going to be far more popular due to their races and they will be able to field more people at all hours of the day. We will see though, but I wouldn’t place all my hopes on it being a whole lot better than GW2.