Lemme get this straight -- I move the mouse DOWN, and I'll start to look UP? What is this, Flight Simulator? This is QUAKE for the love of moms.

I want to kill people with pinpoint accuracy. That means that every miniscule motion must be transplated from cerebral cortex to finger muscles to mouse to USB port to processor to crosshairs. Now, imagine if I had to apply my spatial nervous system into cross-referencing an inverted Y axis. We're adding cycles upon cycles. Furthermore, it's just whack.

While you're at it, why not switch your arrow keys for word processing, or rig your car to drive at full speed when your foot isn't on the gas pedal?