Just when I've read through all seven pages of argument on this topic, the thread falls way off-message...
Anyway, as truly one of the older posters here, I'd welcome a serious discussion board, but I'm not for exclusion based on chronological age only. I've had wonderful discussions on the board with mature teens and adults alike, and I certainly don't want to limit myself to those who see the world as I do. I'm fully aware of the "OMG, I love Idena, Norbert, whomever" threads, but if I quickly see that a thread doesn't interest me, I simply stay away. Self-selection and self-editing is a perfectly valid response.
That said, I do believe that an adults board would quickly find its own level with whatever criteria or restrictions are put on it. In the end, that level will be entirely up to those who post there.
"And the postman sighed as he scratched his head, you really rather thought she ought to be dead..."