Mara is the most sought-after because it's the only chance we have of dealing with Slayer and WL damage with Monstro proc. The Mara's morale rework a) was/is bugged and 2) made aoe morale drain harder and 3) was killed off by the changes to morale damage anyway.
Mara got a slight damage boost as it's the only melee class that gets locked out of either AOE or single target damage depending on stance. It's damage wasn't sky high to begin with and it does big numbers in cities due to sustain rather than burst. It mirrors the SW stance system in the worst way possible. Also Monstro proc is overperforming against some things but when mentioned to a dev it was said it's working as intended so we'll take it. It's a good DPS class, but then Choppas are squishy and MSH are way overrated and WE is legit one of the worst picks.
Then you have small scale 6v6 where supposedly Mara isn't that desired and WEs are amazing. It's like some classes are good in some situations but not so good in others, and City WBs isn't the only form of balance in the game.
edit: regarding the SW: the triple crosscut buff was dumb, even ASWs were saying it wasn't needed. As for the rest of it... the entire redesign was weird to begin with. It killed some of the casual/fun buttons (spamming LA or 100ft aoe SFA) and gained... meh. The SW rework seemed more out of ignorance than bias.
Speaking of bias, up until cities most people were screaming the devs were order biased, and most of the nerfs since cities were introduced have been aimed at destro's advantages (real and supposed).