I would be careful applying the likelihood/consequence formula, because it does not bode well for non commercial aviation. (Commercial flights seem to be doing ok recently though.) Even without the additional risks of UAS operation, private aviation has far from a perfect safety record and represents a logarithmically greater threat to the general public than UAS operations.
Sooner or later all threads evolve into an acceptable risk debate. If you use the "It's only a hobby therefore NO risk is acceptable" argument, you should ban non commercial aviation also. (You should also ban baseball, snowball fights, and the non commercial use of scissors.) If UAS aficionados use "Even if we hit a plane/helicopter nothing super bad will happen and no one will get hurt" argument, get ready for all h**l to break loose when someone does get hurt/killed. (And if Staten Island is any indication, we have not seen the last of manned aircraft/UAS collisions. Although I feel that the risk of UAS operation is minor compared to many other activities, I also feel that serious injuries/fatalities will occur as more UAS flights occur. I believe that a drone could crash a plane/helicopter if a series of very unfortunate events occur, and the more that we fly, the greater the likelihood is that this will happen.)
The sad thing for our "hobby" (and/or work) is that there is a GREAT deal of hysteria. A Phantom dents a helicopter and it's an international spectacle and the cries of restrict, restrict, restrict are heard worldwide. A private plane crashes into a house and kills the pilot and residents and its a local news article. No one screams "We need to stop private planes from flying over people." (For the record I think private aviation is wonderful and do not want it further restricted.)