I think one thing we need to remember is that, making it legal isn't telling people to do it... Alcohol is legal, and look at all the stuff about that! Don't drink n drive, etc. Also, just making it "legal" doesn't mean it will be legal to DRIVE on it... So the "don't want to get hit by a trucker" argument, while a valid fear, isn't really pertinent to the discussion. Mainly because it's just as much a problem wether it is legal or not.
