Technically, it already is for outdoor use in the UK, unless the person flying it is not the person looking at the first person view, as the pilot has to keep visual contact with the aircraft. Also if you use one for anything commercial you are required to hold a civil pilots licence.
This brings up an interesting point. Anti-drone drones may well be much cheaper and more maneuverable than general purpose drones and people in general have far fewer ethical concerns when targeting a drone, as it is basically just property damage. In fact I suspect that some people would even look on drone hunting as some sort of extreme sport.
Another social effect of the introduction of a mass of visible drones is that it has the potential to drive a reasonable amount of an armed and already fairly paranoid population, completely and utterly nuts.
And whatever the police think about how useful these things are, I doubt that having a lot of drones flying around is going to encourage politeness, to put it mildly. A hell of a lot of people fear these things and fear makes a lot of people go crazy.
