Couple of observations and clarifications.
First, I think it's important to distinguish between marketing a product and developing a product. The two are related, but are not at all the same thing. How you market a product is strictly sales. While it's easier to market a product that is high quality, people sell crap all the time. Martial arts is no different.
Second, I agree with those in this thread who talk about the tangible benefits of martial arts training for kids. In my opinion, it's healthy, honest, and appropriate to emphasize the gross motor skills that kids will develop. By all means, highlight the exercise and structure. Self defense? I don't know... that to me seems sketchy. I don't think there's anything unique to martial arts in that area. Or said the other way, I believe that participating in many/most other sports or clubs is just as effective at helping kids deal with bullies as martial arts. There is nothing intrinsic to martial arts that makes it better than any other activity in this area. I've explained this in more detail in the past, and am happy to elaborate now, if anyone cares to hear it. But the bottom line is that marketing the self defense elements, in my opinion, is just sales, and has nothing to do with the actual product. It implies or overtly states that martial arts is better than X activity, when the reality is that it is not. Note that this doesn't mean that participating in martial arts is bad or doesn't help at all. Only that it is no better or worse than any other activity of similar quality.
Third, I think the most effective programs for kids focus on fun, exercise, community, and participation in some kind of sport. The real world lessons that kids learn from BJJ, Judo, TKD, wrestling, etc are EXACTLY the same real world benefits they would learn from football, baseball, soccer, or any other sport. So, it's not about finding the kids who are going to take it seriously. In my opinion, that's a self defeating goal. Some will; most won't, and that's okay. Kids may try it and fall in love with it right away. Most will try it, along with about a dozen other things and that's okay two. The benefits gained are not about commiting to martial arts. Rather, the benefits come from participating in something, whether it's one thing for four years, or four things in four years.
Lastly, all of that presumes there is some actual, tangible product being delivered. Self-defense isn't an actual thing. It's an abstract. Discipline, respect, courtesy, etc... those are not products. They are abstracts. If you don't have a tangible skill being taught and applied, you undermine many of the very lessons that could be learned. The respect, work ethic, discipline, integrity, etc, don't exist in a vacuum. For kids, this (IMO) needs to be very concrete and involve clear, tangible goals and lots of feedback on performance. They get this from any competently run sport. They also get this from any band or orchestra, the chess club, or pretty much any other competently run activity for kids.