I remember the time when I was trying to reach 1.850 rating to get t1 weapons, also remember the time when I was struggling to get 2.2k, those were the times when , at least for me, the rating mattered. Then blizzard decided the game is too hard for average player and started simplifying it to the point it become so easy and so forgiving that anyone can play it. In my opinion ,if you take away the possibility to distinguish yourself from others by being better player than them, than what is the point of competing? You can introduce as many mounts and achievements you want, if you don't make them hard to get , they will NEVER be unique (if majority of players can obtain them that is). Thats why I think there were more people playing this game both pve and pvp-wise when it was hard to get certain rating or PVE content done, they were whining on forums sure, but they didn't quit playing because they all wanted the same thing "to be that guy". This is in the past now, and anyone can get gladiator now with a FOTM comp, bug(that takes 1 month for blizzard to fix),DDOS, win-trading or whatever. And its because of this lack of "uniqueness" that I think people quit the game once they reach their goal.
The only thing keeping PvP alive in this game is Oil Money and for PvE well those people are also gonna leave sooner or later, just a matter of time for this game with no future and no Esport support what so ever to die. (1 tr and 1 tourney a year is by far not enough to keep a scene alive)