Good Day sir tallest
You might try starting your own discussion threads in the forums for a while and keeping a tight reign on the tenor of the discussion. What I mean is this -- it seems to me that whoever starts the thread is responsible for setting the tone. You, as the originator of the thread or forum "host," as I sometimes think of the person who originates the thread, should set a positive tone and perhaps the participants will follow suit.
That's the theory, anyway. I prefer this Q & A section myself. I think its a lot more fun!! I don't forum as much as I used to when I first joined HubPages four months ago.
Something else you might consider: if there is a question being taken up in a forum that interests you, and you find the alleged "discussion" has deteriorated, as it usually does (particularly in the politics and religion and philosophy forums), simply write a long hub about it yourself and carefully examine the issue from various angles. Make it good and pretty with nice pictures and a video or two (if appropriate) and you may attract a lot of thoughtful comments; and you may find that you can have much more satisfying and intellectually stimulating discussions in the comment section of your hub(s), as a see several hubbers do.