RE: could they actually be good in this regard?
WRONG kind of toy for a kid to "Cut his teeth on". First off, I think they're really more dangerous than a bow. Secondly, you're starting them off lazy. A kid doesn't care if he nails a bullseye everytime he shoots. He just wants to make believe he's Robin Hood or Sitting Bull or something like that. He wants arrows down range, something he can feel and control. Something where he can have an occasional good shot and get excited about. The type of weapon isn't what limits the number of kids getting involved, it's having an adult who will help them and encourage them. You teach them to shoot a crossbow, that's what they'll use.