I think it teaches the wrong approach to pitching and in higher levels you rely on the FB and not on the CB. Look at Smoltz -- when he started he would throw maybe 20-30 FB in a row without showing the team anything else. Hell, Gryboski gets away with a FB w/ movement and nothing else for once around the order.
Also, when not thrown correctly it can lead to arm trouble. A lot of the coaches who teach it young don't recoginze what's thrown well or thrown wrong, so that depends on the coach's experience.
But it's easy to not gain arm strength during those formative years by not throwing enough and not throwing enough FB's. That's my real concern, along with the approach to pitching.
But in my opinion, Little League should just be a different freaking sport and should be looked upon as a different sport. The emphasis is on different things and the kids that succeed there are more often the kids with the full beard by the time their 10 and then when everyone is 18 and in high school, the playing field has evened out and then you can see who can play. Too many parents living through the kids at that age and too much pressure for kids who aren't mentally mature to handle it. It's amazing how other adults will use those kids and I think for alot of the kids don't understand who is in their corner and who just wants to be 'friendly' because the adult thinks the kid can help win a championship. Say what you want about Danny Almonte knowing right from wrong, but the freaking parents take advantage of a kid like that -- whether he was 12 or 14 he's still to young to make his own decisions when surrounded by overzealous adults.
Anyway, enough of that.... I say throw FB and maybe a change around 11 or 12 but just play tons and tons of catch and learn to control your body and have some kinesthetic awareness and hopefully you can throw strikes. Build on that later.