Some liberal disappointment was due to the increasing body of evidence relating to the President's incompetence. This was among only the relative sane liberals, however.
Among the insane wing of the Democrat party -- about half of them, it would appear -- the source of their disappointment was as you say.
Their Messiah failed to a.) seize BP and b.) shut down the rest of the oil industry (he only snuffed the deepwater offshore business). You can read their comments on some blogs and articles. They wanted the supply of petroleum to dry up -- so we would be forced "to go green and save the planet."
I suppose they all already have their bicycles, their wood stoves and eat cold tofu.
There is a strain of insanity abroad in the country...
Do they not understand that if they do that, everything in this country is simply going to STOP? Obviously they don’t remember the gas lines, the inflation. But they are going to be in the hurt locker too.