Yes they can be a violation of privacy. There are stories in the US of people shooting them down heh. Personally I do think it's okay to fly them around in wide open spaces where there are few people, or just in the back yard etc. But over someone's property isn't a good thing at all.
In terms of govt. collecting video on you... well they can do that from space anyway probably (I have no idea though). Maybe insurance companies will get in on the action to reduce claims...
Currently it's very difficult to be able to use a drone for commercial use. One needs to jump through many hoops and licensing is expensive.
They are becoming useful in agriculture, mining, film, disaster response etc so I'd say they're likely here to stay. Just not sure about delivery stuff. Payloads and flight time are small and they're dangerous.
Guess I'm an advocate, but I wouldn't mind seeing them shot down either. Maybe in the future instead of duck hunting, we'll have drone hunts. At the moment they do have drone races (I think there was one in Dubai recently), so maybe gladiator-esque drone fights are also around the corner...
