We're still in a stage of experimentation with intellectual property. Is there any functional difference in the rental of a game that is on a disc versus one that is solely digital? By this line of logic, then the sale of digital goods also makes no sense.

But seriously, the reason I've not tried out Direct2Drive is I already have Steam on my machine, and I didn't see the need of both services. If GameFly offers a streaming only plan ala Netflix, I might get interested. Perhaps Valve could conjure a similar system?