Do you miss something on BrainKing.com and would you like to see it here? Post your request into this board! If there is a more specific board for the request, (i.e. game rule changes etc) then it should be posted and discussed on that specific board.
I can see both sides, but overall, I'd say a kids board would be a good idea. Without going into detail, there are many chat rooms on the net where certain types of people prefer to prey. I doubt a games site where the huge majority are adults would be much interest to them. Especially once they realise how heavily moderated it would be. A bigger concern is private messages, I like Scarlets idea of needing parental permission before an adult can message a child - and also parents should have to give permission before their kids can message adults. I'm not sure how easy that would be to set up though.