The inherent proposition is that landings are hard. Why not just land in powder? That solves the problems. If you don't have pow, there are many things you can do to obtain some.
My guess is that the sense of accomplishment that comes with dialing in a new trick is cheapened with these airbags (what fun is this if there is no danger or difficulty to it?), and that they will only promote crazier and riskier tricks on actual snow, therefore creating more danger than is there now. However, I would have a fun time moondropping into one for an afternoon.