Alison Milbank has a terrific piece on The Hobbit and Christmas, and how The Hobbit warns against materialism and the lust for gold. Christmas, rightly understood, is the best antidote to such sickness, as generous giving and receiving dissipates greed and selfishness. We should enjoy the things of this world, but not too tightly, so that they may be shared.
What complicates such gift giving is our world of credit, where we can be generous now because the expense has been pushed to the future. Why not buy and borrow, since it won't come due for 18 months? Much of our Christmas generosity, I fear, is out of credit and not sacrifice, as people lavish others with gifts they can't really afford (and aren't really current sacrifices, but future ones). Generous gift giving, when achieved through impractical lines of credit, becomes a greedy materialism in a new form, and isn't always an antidote to dwarfish avarice.
Bilbo's world (and all of Middle Earth, for that matter) has no concept of credit or complex markets. It is a simpler, artisan world where we are not alienated from our work, and where industrialization has not corrupted a simpler economy and work ethic (at least, until Saruman reappears in the last section). True gifts, perhaps, must come out of sacrifice, where the gift is irreplaceable, as with the Arkenstone. But in our current economy, we are tempted to buy two Arkenstones, one as a gift and one for ourselves, and use cheap credit to do so. Is this still the same gift as Bilbo's, however? I don't think so. It is no longer a mark of the true world of sacrifice and scarcity, but a false abundance to paid by our future selves.
Additionally, Bilbo's Shire is still lacking, despite its generosity and relative immunity to greed. Bilbo plays it safe, and is contentedly bourgeois until Gandalf shows up and forces him into an adventure. Bilbo's life is without risk, and there is a bit of self-critique here for Tolkien, that as much as he might see himself as a hobbit, he knows that we are to see ourselves, and our lives, as a grand adventure, and to take risks where need be. Avarice is a sin, but so is self-satisfaction. The risk of taking a journey, such as Bilbo and later Frodo's, frees us from indolent aseity. As Milbank notes, the Shire must be made strange and riddled, so that it is seen as part of a larger journey and risk, and not just a smug, self-satisfied existence.
Bilbo may have much to teach the dwarves and the world about greed, but Bilbo also has much to learn about life as an adventure.