Interesting article, indeed.
I dont know whether they serve as weapons of high effectivity against buildings, but against crowds etc. they surely would yield.
Before becoming a pilot, in my youth, I imagined all kind of wierd stuff to do with model planes (of course I was a dedicated a/c model builder in the DAEC, one way to obtain junior flying school permits at 14 and sponsored at that time): Spying on neighbours, live dog fights with real ammo, smuggling drugs from the Netherlands, etc.
While the technical side did not yield during the 60s, most of what I dreamt of is possible/feasible today, much of it standard and cheap:
For just 299 $ (200 Euros) you can obtain your own UAV, an AR drone, my current favorite (from my first money next month from my new work I plan to buy one and set up a AR drone center here on the island) that - steered via iPhone, iPod, iPad or Android - does live dog fights (like a vid game where you electronically "splash" your oppnent), can spy at the young lady opposite that always takes a nekkid sunbath on her roof terrace, etc...
Here some vids showing all the aspects I mentioned, the toy from my childhood dreams:
So, I think yes indeed those a/c can be used for all kinds of purposes, productives (like aerial photos), to illegals (spy cam ready) and also as terrorist means.
Asking now for the prohibition of model craft I find very strange from the Americans, isn´t it their credo that it is the person that does harm, not the gun?
Rattler