I don't think the game has been getting worse because of Activision, because if that was the case, they're doing an extremely slow job of "destroying WoW." The fact is that Blizzard is no longer staffed by the same people who were there during WoW's heyday. Legion was very recent, and it was quite good.

I do think that Blizzard has taken a lot of attention away from WoW's development owing to the huge success of Overwatch. WoW's no longer their main product and I do feel like it's causing some of their other franchises to suffer. (Especially Diablo lmao)