Because it actually does affect me. The existence of this tool totally destroys forming groups outside itself, because it is the easier path (and by far not the most enjoyable one). It streamlines group formation to the process of clicking a button. You don’t have to talk to anyone, you don’t even have to know where the dungeon is. It then creates this behavior of facerolling content like you are in a production line and you don’t have to think about nothing.
Then dungeons had to be dumbed down to a conforming state so people can clear it, and you don’t even need to use 10% of what your character can do to finish it, because when something goes wrong what happens? The tank or the healer leave because joining another group is as easy as pressing one button. No doubt people hate leveling when it is this boring and flawed.
Of course there are many other things that create this kind of environment, like others mentioned in this post, but LFD/LFR is one of the, if not the biggest, ofensor of creating this environment.
So yeah, it does directly affect my enjoyment of the game.