Paying you a daily rate pro rata for any leave you lose should have broadly the same effect, with appropriate checks in place to ensure that people can't deliberately avoid taking leave.
I asked that specific question to the AFPRB a couple of years ago and was politley but firmly told by the Chairman that there was no chance of it happening because it would lead to weak management of leave.
I did turn that one round and ask what about those units deployed on ops where there is no chance of taking all their leave and where because of that the bosses are refusing all applications to carry over leave in excess of 10 days as there is no chance of taking it without impacting on unit efficiency. Again, firmly refused. Unfortunately, I know of units where it is still going on, and guys are losing leave through no fault of their own, just purely down to the length of time they are away (I wonder if that counts as weak management of leave by the high paid help
? I suspect not somehow).
It would be interesting to see just how much the MOD is saving / making through this policy. If it happened to me (may still yet - my application is in at the moment!) I would consider billing the MOD direct for my services for the leave I have lost / free labour they have gained.