Surely, at least half of you know my story by now, but I'll tell it again anyway. (Sorry, I'm not just into talking about myself, there are just a lot of topics like this!) I left after achieving 1st dan at my dojo. I was only 12 (It had still been 6 years, my dojo doesn't just hand out black belts), but ironically, that was the goal that I'd set up for myself when I started, and being then in middle school, it was just too much for me to handle at once. So I went back to visit in January, and all of the instructors remembered me. So I decided to go back. Of course, it was a while before I got back into shape. Anyway, that's how it went with me. I find that, when you are a little kid doing karate, or any martial art, there is indeed a social aspect to it. Most everyone is high energy, and very personable in the dojo. I went to all of my senior friends' black belt graduations and other such things. The point is, for little kids, it really is up to what they enjoy doing most. It really is too bad, but that's the sensei's decision. If you haven't already, I would suggest that you should point out some of these things to him or her.