Relmstein recently talked about many people's least favorite concept in WoW: the PUG. The premise, it seems, is that because raiders don't need the gear, they are not running with pick-up-groups, and those that do need the gear tend to run with their friends. The looking for group module is therefore filled with people that don't have a friend's list full of associates willing to help them, and those that don't have the experience raiders do.
Now here is where I have to agree and then disagree. On one hand, it is true, raiders tend to not run the 5-mans, at least in my experience, because they already have the gear. But there are plenty of excellent players out there that don't raid. While raiders are working to be the best at their particular class for a specific purpose, it's awfully elitist to assume that just because I raid I am therefore a better player. A commenter on the article mentioned a very valid fact: being a good player doesn't only mean that you know your class inside and out. There are also the other pieces to consider, generosity with loot, patience with new players, the ability to communicate with the group. And also, who's to say that there aren't raiders out there that enjoy running instances with people they don't know simply for the joy of helping others?
Relmstien goes on to say that the changes to the reputation requirements for heroic keys and the addition of daily heroic quests will go a decent way toward luring the better players back into the 5-man instances. I'm not so sure about that, seeing as how heroic badges will be dropping in the 10-man instances as well. I don't know that there will be enough incentive to bring players back to the PUG.