I definitely don't envy those who have to go it alone in the dungeon finder. WoW PUGs have always been terrible, and Cata heroics being hard for those that still need gear from them have been kinda too much for the average PUG.
I think you'll like Cata rather much, Taly, as far as WoW goes. The new quests are all pretty high quality and everything is tied together a lot more from a lore perspective. The end game is better IMO, but it is a lot more daunting now than before if you don't have other folks around.
That said, for whatever it's worth, they're giving random dungeon finder groups a buff in the patch this Tuesday. For every random person in your group you get a 5% buff to damage, to healing, and to health, with a cap of 15%. This was done to address cases like Rodahn's. Preformed groups tended to do fine, even undergeared, but PUGs were kinda bad. A 15% buff is no replacement for actually CCing or using skull/X targeting icons or assigning anyone to do important things on a boss fight, like the last PUG I was in didn't do, but it should be a help.
Man. How do you not even bother marking Skull and X. Even in Wrath we did so DPS knew which one they could hit without stealing aggro! Then that tank got all offended and left the group. Grumble grumble. Last time I try and help a guildie by queueing with them.