I'm going to be playing Brink on PS3, and while I agree in principle with most of what you're saying, this part can be proven wrong.
With appropriate controller sensitivity on Resistance: Fall of Man (a PS3 exclusive from the console's release lineup), a skilled player CAN circle strafe and consistently headshot an opponent. Many players prefer to lower their sensitivity to improve precision, but if you're comfortable enough with the controls, you can aim accurately enough with the sensitivity high enough to circle strafe a slow-moving target. If they start running when you start circling, you'll have to change tactics, but that's the same on PC, you can keep circling unless you can outrun them, can you?