Here's why, to several posts in this thread,
- villain side is drab and flat. No variety, few zones and the content is unengaging. Arachnos are a groan enducing Grindy pain slog to fight, continuously. And, snakes? I'm fighting stupid man-snakes, over and over? Sweet tea, couldn't you think of ANYTHING else?
- villain AT's have their interesting points, but by and large lack vibrance, depth or dynamism. While they are fun, they aren't as multi-faceted as hero AT
- Perez park, hollows, croatoa,... All were very popular before the devs originally began to try and make everything easier... Easier, faster easier. It was a normal thing to have to go to hollows, then on the faultline maybe or steel, then off you go to croatoa or bricks... Now, the "play your way" precedent has emptied zones that yield sub-optimal results for many. Then, new players only know what they see, and they never see those zones because "zomg dfb, LFM!," And "dib, come get your super xp!" Granted, croatoa and hollows are sloggy at times.
- Perez park never had any real meaning, and let's be honest, the goddamn Forrest is a pain. But still necessary, because it's different.
- boomtown is just sad.
In the end, villain side suffers from lack of material attention and innovation. Zones like croatoa, hollows, striga and hollows suffer from the devs continually trying to serve cries for instant gratification. Put back some guiderails, and blue zones will repopulate. Make certain goodies villain side only, to attain, and people will go. Add depth to villains, and more will stay.
Don't even get me started on Pretoria. Great idea, but game coders are often not good story tellers.
Edit: as another thought, villain side is all about how Lorde recluse, stupid name, wants to rule all. And you have to kinda be in that world. Blue side you're just a hero in a world that's fighting back and working.... In a bunch of ways. No required path. I'm pretty sure if blue side were all about how statesman had a grand scheme to rule all, and you had to be in his army, it would be repulsive. Villain side should have been a reverse mirror of blue, where you're the antagonist and you're just working to... do what you want. As it is, you're basically subjected to arachnos will, over and over. Represive.