While not necessarily for Wildstar but many GW2 players, and MMO players in general, go deep on ESO because of how bad it is, and it is justified I guess. Its just an opinion about something and people love to get defensive if they like the game.
But at the end of the day, people that like a game will defend it no matter what. That is why people that play WOW think WoW is the best. That is why people that play GW2 think GW2 is the best. That is why people who are playing Wildstar think Wildstar is shaping up to be the best. It will also happen when EQ: Next comes out too. Heck if you want to see a beacon for positivity for GW2, just go on reddit where most criticism is down-voted but I guess this is nullified by how much negativity comes out of the official forums as you have stated.
Personally, I do think GW2 is the best MMO out there at the moment and its positives far outweigh its negatives. I wont comment on the Polygon revised review because I think Polygon is a joke being a Sony fanboy, but I acknowledge that an MMO has little to do with Sony/MS. I just think people are way too defensive with GW2 especially with Wildstar coming and EQ on the horizon and combined with the new WoW expansion there is seriously going to be some REAL competition for GW2. I hope the devs at ANET will step up to the challenge and the first step is to improve the forthcoming Living Story that many people cared little for and also why many people dislike the game. Competition will hopefully breed excellence.
Am also a little peeved at ANET at how they nerfed the Mesmer into mediocrity in the meta and the promised bug fixes never came too. If you want to see genuine negativity, check out the Mesmer sub-forum.
There's really no competition for ANet with Wildstar or the upcoming WoW expansion. The people playing GW2 play it for a reason, because it's not the same old shit they've been playing for many years now. I also hardly think "many people" cared little for the LS considering the amount of people who logged in every single update was staggering. If it were really so few people who cared, we wouldn't have seen countless overflows for new content every single update. The people who aren't actively playing GW2 are likely not doing so because they want a trinity based game and one with vertical progression. They may or may not go back to WoW or try out Wildstar, but it won't have an impact on GW2 because those people no longer play GW2 anyways. Now EQN on the other hand could potentially pull people away from GW2 but it could also very well co-exist because it shares some of the same philosophies and is F2P. Though EQN is likely 2 years out at this point.