Devs started making changes that killed a lot of fun to, presumably, appeal more to CoD players. Some of the balancing decisions also made a lot of the guns a bit less exciting to use and made most of them essentially the same thing. The two most popular classes (medic and sniper) have been nerfed to oblivion. It feels like they are trying really hard to curate a very specific experience, and that seems to have burned out a lot of people or driven others away.
Personally, I think they should have leaned harder in the direction of more realism and rewarding creativity.