In short, WoW has transitioned to being run by people who don't play the game, don't understand people who do play the game and are targeting the game at people who don't play the game at the expense of those that do.
LFR undermines both the aspirational part of the game, which is extremely important, and the social aspect of building relationships, which is super-important and the real reason most people stick around.
Now we have 4 raid levels (LFR, Normal, Heroic, Mythic), which is too many. The differences are largely cosmetic and minor ilvl bumps. There are some unique items in higher tiers, to be clear.
Lastly, LFR is essentially an interactive cinematic. It's part of what I like to call "conveyor belt content". There's no choices to be made. The outcome is almost certain. You may as well be watching a cinematic. This probably goes well beyond LFR.