What role did greed play in Tolkien's books?

[William Cloud Hicklin]

Bilbo appears to hold to his stated earlier resolution that he took his fourteenth share and disposed of it. He would only accept two small chests, one of silver and one of gold, as a reward. Perhaps this was a symbolic payment for his rescuing the dwarves both from the giant spiders and the Elvenking's cells, something he pointed out was not included in his original contract.

Well, that and the fact that Thorin did, eventually, get the Arkenstone.....

Worth noting as well that Bilbo gave away his share of the Trolls' loot, feeling that he had "received stolen goods": not the act of a greedy hobbit.