Plain and simple to me, I box so I can avoid people when doing 5 man instances. Even with the new system, you still can run across idiots who mess up a run. When you box, you control everything. The loot, the pull speed, burn order, afkness, etc. To me there is nothing like being able to hop into an instance anytime I want, take a break during it when I want, and end it when I want. Get hungry during an instance, no problem! Someone at the door, no problem! Significant other need something, no problem!

New LFG system or not, you are still getting paired with the same people from before. It did not change the people you would be running those instances with. So until they can do this, any group outside of friends/guild/boxing will always have that question about how good the group members are.