Oh please. First, the OP stated "it is entirely possible that a car could speed around a curve and hit someone skateboarding in the street." That was what I was referring to.
Second, there are a whole lot of "if this" and "it's possible that" in this thread. So how much damage has actually been done by these vicious skateboarding kids? How much damage can they even potentially do compared to the distracted soccer mom juggling a cell phone in one hand and a latte in the other while she "drives" a van (or Hummer?) full of screaming kids around those narrow corners with no room? If you want to ban potential causes of damage, start with what can "potentially" cause the greater amount of damage.
I'm glad that you don't speed through your neighborhood and you watch out for others. But that doesn't mean that ALL motorists in your area follow the rules of the road. Similarly just because SOME people on skateboard or bikes or roller-blades or ... cause problems doesn't mean that ALL people using those modes of transportation are causing problems.
We've had our share of problems with some kids on skateboards. One of my neighbors who uses a skateboard for some of his transportation went over and had a talk with them one night. Problem solved. No ban required.
FWIW: I am a League Cycling Instructor for the
League of American Bicyclists BikeEd program which is the only nationally recognized bicycling safety and skills education program in this country. While the League program doesn't really deal with skateboards and I don't ride one, I have personally been involved in some local skateboarding issues and I feel that skateboards are a valid mode of transportation. Trying to have a blanket ban on them just because of the behavior of some people on skateboards doesn't seem like the best solution to me.