It's not as simple as just adding a connector. You also then have to provide drivers so the PC's that connect to it will be able to read it and communicate. They could likely use some third party package that's already in the great USB database in the Microsoft sky, but that will likely add more cost. Keeping it serial let's them keep the focus on their bread and butter, the price to performance ratio. Also, they're not a company that is constantly pushing out updates so most people will likely NEVER use the feature anyway.

That said, when the 975 firmware update was put out, the Outlaws sent me the USB to serial adapter they wanted me to use for it.