Just because there is a new toy that is out, that happens to have the name of a controversial military device it becomes a major threat.
First, before I get mauled, I'm not entirely crazy about this new proposal. Under a particular altitude and as a hobby I think we should leave unregulated, that said... The drone market is filling up. Drones have way more people in it than the model rocket and RC Airplane markets and I would dare say combined. Drones are also a lot more industrious than say the model rocket or RC plane. Drones are being used for photography, to move goods, be the ultra creeper you've always wanted to be, traffic reports, and so on which are all way more than what the model rocket and RC plane market have ever done.
So considering that the drone market has been able to do all of that and the others are a no go, yeah I can see why the FAA feels there is a need to regulated it. Now that's not to say the others can't do that, it just to say that they haven't, if and when they do, then I'm pretty sure they'll start regulating that as well. But let's be very clear that this comment isn't a voice of support or disdain at the regulation. It's that you can't very easily compare model rockets, RC planes, and what have you with the drone market simply because they are vastly different markets. People have found drones to be really useful and have started creating a lot of points where they intersect with everyday life. The same can't be said for those other markets.
For those who like rigorous formulae on why anyone does anything, I would say (and simply my opinion) that the FAA acts when a particular class of aircraft is used in X number of applications that has Y number of general public using those applications and there are Z number of opportunities to purchase that class of aircraft. (I know really rough formula there, I don't espouse to know what goes on inside the FAA's head) However this rough formula would say that as any of those values X, Y, or Z increases, the likelihood that there will be regulation increases proportionally. Drones are "X" used in numerous applications, "Y" are criss crossing the general public a lot, "Z" you can buy them pretty much everywhere. I'm pretty sure the same could have been said about bi-planes in the early days of aviation.
Again, I'm speculating here as to the logic because it would be wrong for us just to assume, "Hey I'm government and I just want to regulate anything and everything I can possibly." If that was truly the case one would think we'd have a modern Stamp Act. However, considering that we are talking about a public entity, we could forgo the speculation and render my entire comment useless and just simply write them an email asking, "Hey what particular factors does your agency feel led to the regulation of drones and not something like RC airplanes or model rockets?" Again, this just my two cents, I don't condone or condemn this new regulation, just speaking purely out of the these things you talked about model rockets and RC planes != drone market and for better reasons than it's named after the thing we use to murder (don't get me started on that) people around the world with.