I can think of a few reasons: 1) You can tailor the wireless protocol to exactly your needs, rather than using something general purpose. That can help things

I can think of a few reasons: 1) You can tailor the wireless protocol to exactly your needs, rather than using something general purpose. That can help things like battery life and latency. 2) You don't have to work with buggy Bluetooth hardware or drivers that you don't make, and your hardware works with any computer with USB. Bluetooth was not common on PCs for a long time, especially on the desktop. 3) You can ship your peripherals pre-paired with the receiver, which means users don't need to do any setup besides plugging the receiver in.