Those who claim to be "casual" and don't want to devote more time and effort to doing Normal, Heroic, or Mythic. It's not that hard to imagine.
I suppose the argument could be made of "it doesn't take that much more time and effort to do Normal, Heroic, or Mythic" than it does to queue up and wait for LFR. However, that extra amount of time and effort is experienced differently by different people, and the path of least resistance towards being able to experience raid content in most cases is LFR.
It's not going anywhere.