That's exactly what a bonus is: part of your salary that your company can at it's discretion not pay you. Marketing and HR has spun this into the sham that it's

That's exactly what a bonus is: part of your salary that your company can at it's discretion not pay you. Marketing and HR has spun this into the sham that it's some kind of additional benefit, but it's not. It is directly at odds with the individual employee's end of the risk / reward trade off, and he should almost always reject it in lieu of some other form of comp.