Have you done Normal or Heroic modes this expansion?
I assure you, the average PuG group would be 100% stonewalled by even the easiest heroic bosses. They would struggle mightily with some of the more difficult normals, too (Will of the Emperor, Lei Shen, Iron Qon, Durumu). There's no point in these difficulties being queueable if they're impossible for that audience. It really has nothing to do with skill (Although the average player's skill is vastly lower than necessary for Heroics). Coordination is the problem. You can't get a group of random people to mesh well enough to tackle real content.
LFR groups are already a nightmare if you don't manage to get in with raider alts on Tuesdays. I made the mistake of waiting until Monday to do LFR on my alt last week. Huge blunder on my part. I think I spent over 2 hours in ToT2.