Lobbyists who represent the powerful wholesalers wield far too much power in state legislatures for the laws to be easily rewritten or overturned. Letter-writing campaigns to elected officials have so far been largely futile. Other wineries detest the power the wholesalers wield in selling their wares. Small to midsized wineries would like the freedom to ship directly to consumers because their profit margins would increase if they could sell their products at retail prices instead of wholesale. As it is, small wineries don't allocate enough cases of wine to small markets to impact wholesalers' finances.
Wholesalers make their big money on larger-volume sales.
By going direct, small wineries could also circumvent the influence of the wine media, which some still view as a hindrance to their sales campaigns. Still, many of these small wineries are the precise brands you'd like to have direct access to. I don't think most wineries would want to become direct-shippers exclusively because they appreciate the diversity of sales in wine shops and restaurants. The hope now among free-traders is that a federal court will strike down the laws prohibiting interstate sales of wine. Just recently a judge in Massachusetts dismissed a suit against FedEx, the shipping company, and an Internet wine-sales firm.