I asked this question when the expansion first hit: do sockets suck? It seemed to me that there were lots of socketed items in game that, even with great gems in them, just didn't match up to the nonsocketed items I was finding.
And now, Passion of Anub'Arak posts on the forums with much more concrete evidence of exactly that. Even the epic socketed drops in Karazhan, with great gems in them, don't have the stats of some of the nonsocketed drops from the level 70 5mans. There's no point to wasting all the time, consumables, and gem money to get the higher level items if a run through a 5man instance will net you better gear.
Fortuately, Neth replies in the thread, and says that item balance is still ongoing. Unfortunately, she (I'd imagine she did it on purpose, tricksey CMses) goes right down the middle, and says that they'll be looking at items "that may not be living up to what we wanted them to be or are more powerful than originally intended." As for whether that means they'll make the epics dropping in Karazhan even better (yay!) or nerf the 5man drops (boo), your guess is as good as ours.
As a final note, I'll just throw out there that this one may not actually be Blizzard's fault. The availability and price of good gems depends on how many players are jewelcrafting, and how often. It could be that everyone tried out jewelcrafting in the beta, and so Blizzard figured that jewels would be better or more plentiful that what's out there right now-- with not enough good jewels to go around, it's no surprise that socketed items are disappointing.