What do you think of the dwarves reluctance to go back into the caves to find bilbo?

The dwarves didn't want to tangle with the goblins again. They were afraid of them.

"You would have dropped him," said Dori, "if a goblin had suddenly grabbed your leg from behind in the dark, tripped up your feet, and kicked you in the back!"

"Then why didn't you pick him up again?"

"Good heavens! Can you ask! Goblins fighting and biting in the dark, everybody falling over bodies and hitting one another! You nearly chopped off my head with Glamdring, and Thorin Was stabbing here there and everywhere with Orcrist. All of a sudden you gave one of your blinding flashes, and we saw the goblins running back yelping. You shouted 'follow me everybody!' and everybody ought to have followed. We thought everybody had. There was no time to count, as you know quite well, till we had dashed through the gate-guards, out of the lower door, and helter-skelter down here. And here we are-without the burglar, confusticate him!"

The dwarves felt that he had already been too much trouble to everyone and did not want to fuss with him anymore. They felt a great reluctance to encounter the goblins; they simply thought Gandalf had brought along a useless companion.