Its great for businesses to deploy to their employees, not just not too practical for your typical consumer. Since the consumer demand really hasn't reached a level to that of a business demand, this is why you won't see a fall in price structures for a little while.
I use a Razr V3c with T-mobile and can use it as a USB modem. I've never really had to use it for anything other than taking some pictures of a house for a 3rd party. I was about 2 hours away from where I needed to get the pictures too and rather than rush home to send them, I just connected my phone to my laptop (I installed the V3 driver previously assuming that I would need it someday) and then emailed the pictures out to save time.
Another than the practical business uses like on-site insurance estimates for small and large claims, on-site computer repair, etc, there really isn't much of a personal demand for it.
Other interesting use was for a system that we installed while I was in Washington. Our client was the
Washington State Ferries. The problem was retracting their food sales off of the boat while they potentially could be smack in the middle of the Puget Sound. The solution was to go with Verizon's service with an antenna array that we stuck on top of the boats. This enabled all of the point of sale servers to maintain a constant connection to their VPN, WAN or just to be able to be reached using a Remote Control software applicaiton.
Let's face it, cell phones these days are coming out with browsing packages and capabilities that really (so far) exceed typical consumer use.
The use of my phone as a USB modem is included in my plan. Not really sure how much extra it is. Perhaps $4-$5 a month? It's not expensive, just not something that's typically included as a base package.