WoW finally has the structure in place to support different content and difficulties for different audiences. Many of the problems they've had over the past few years with content which involves any kind of moderate difficulty (and therefore requires some level of teamwork and cooperation) is down to the fact that Random Matchmaking throws groups together which want different things; some players just want a speedy gear run, other players want to do content properly, some players are just deliberately out to troll/grief, others are completely clueless and want to be boosted, etc.

Players come out of LFR/LFD with such a negative view whenever their group fails that they blame the content being "too hard". Pickup groups and groups involving friends/family/guilds/etc don't have that problem because those groups are formed and controlled by players themselves.

Blizzard have already announced that they want Random Matchmaking to be a 'last resort' and put the focus back on the TBC/WotLK style of group building (with the new group finder tool). Flex Raiding and Heroic Scenarios have already been a success - the next logical step is to go back to challenging 5-mans without LFD.