Definition of bonus. : something in addition to what is expected or strictly due: such as. a : money or an equivalent given in addition to an employee's usual compensation.
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I used to work for a company that had a "quarterly bonus" program.
6 weeks into the relevant quarter you received your bonus (and you had 6 weeks to do it, not a quarter) which consisted of 20-30 hours of extra work you had to do to get paid $750. In addition to travelling, working 60 hours a week onsite, and usually 230+ hours per month total.
Now, their "bonus" program was "optional" so near the end of my time there, a lot of us would just walk away from it, and not complete anything at all. It drove our managers nuts, as we figured out that they assigned us the critical work that they had to do to get their bonus money.
When you give someone something on a regular basis, and treat it like a salary as was probably done in the UAL case, you shouldn't be taking it away and replacing it with this lottery scheme.
Then again, if you can afford to, you can just quit if it's really "that" big a deal.