Many of my compatriots have noted how unsocial the groups are in the new dungeon system that automatically groups people together. I have noticed the same, and in fact, that's why I'm still doing runs with guildies on a regular basis. The other thing about running with these anonymous groups is that they go so fast, you can't even pause to comment in guild chat. At times, this isn't a problem. After all, the point of these runs is to get emblems and most people in the groups have run these dungeons plenty of times. Often, then, the dungeons are just cruising along just fine; there's no real need to say anything. But I've been in a few groups where some communication, even if just about the task at hand, is definitely in order.
Once I was healing a dungeon where the tank wouldn't wait for me to get mana before plowing ahead into the next group of mobs. He died once as a result, and then yelled at me for not healing him. I yelled back that if he wanted me to heal him, he needed to wait until I had the ability to do so. I'd said something a number of times about this. If he'd been paying attention, which I don't think he was, he would have known that. One of us, him I think, quit the group over that. And the next tank we got was great, waiting for everyone to be mana'd up before beginning a fight. And I've seen other situations where someone should probably have said something before someone else messed up and got us all killed. I saw a druid aggro an extra group or two, making healing super challenging for me. And I've seen the less traveled dungeons, like Oculus, fail pretty badly. Actually, my experience with Oculus has been that as soon as people see that that's the draw, they quit. I popped into one where 2 people had already left the group and another person was saying this was their first time in it. I quit that group. It would have been hours of my time, just gone!
Some people are saying that the new dungeon system eliminates the need for guilds. It might for some people, who are in the game just for the game, but for people who like to hang out with others virtually, guilds will still play an important role. It's a little like IRC chat with a game in the background. And the harder content, raids and the highest level dungeons, are still better to do with a group you're familiar with. So guilds might change, but they'll probably still be there in some form.