Everyone wants to blame a particular system or change, one they dislike, for WoWs decline. Wow has been declining for a long time through many new systems and changes. Sure, some of those caused people to quit but I think WoWs real enemy was always time. The game is really old at this point and when it first came on the scene there were not anywhere near the number of other MMOs. I bet most people left not over any one system, but because there are enough MMOs out there to find a niche specifically for themselves.
Don’t like M+? The devs will never hear you on this forum. Speak to them how they will hear and go find and give your money to that niche MMO that fits you perfectly.