Well, as I said, during the Alpha there was something like that, left click serving as the primary trigger. After left clicking the clipboard off the screen all the guns blazed as long as there were rounds left. Having the mouse as a default controller would cause every one having a joystick to first unmap all functions from the mouse to get to point zero. It's much easier to write a small tutorial about configuring any controller, including the mouse. After all, a mouse and the keyboard aren't the first intuitive devices to fly an aeroplane, be it virtual or real.
I truly appreciate the skills of you guys who are playing with a mouse only, but for me and I believe the majority of us the mouse is just for pointing and clicking. Assigning several modes like "fly" and "point-click" by default would cause issues, at least for guys like me.
When I was much younger I tried to play a rally game with a friend on a shared screen using a shared keyboard. Left-right-accelerate-brake only, no up-down-tilt movements. Need I say that we both sucked badly?
