The big distinction isn't between music threads and non-music threads. It's between threads that are getting somewhere, and those that aren't.
Non music threads can involve discussions that get you understanding the thinking of people you disagree with and provide you with information you'd never get anywhere. Or they can be repetitious and boring and filled with people having temper tantrums and playing silly games. And there's any number of other varieties - funny ones that are funny and unfunny ones that are intended to be funny. And of course the whither-Mudcat ones, like this, which recycle the same arguments, but sometimes move on fractionally.
But the music threads are just as much a mixed bag. There are the song searches that bring fascinating stuff to light, and the musical technical stuff, including of course ones around health issues that affect music. An there are the listing ones about who-is-the-best, who-is-your-favourite, which I tend to avoid. And the ones which come on as music, but they are really about nostalgia and ancient television programmes. And the perennial what-is-folk, which is the music equivalent of whither-Mudcat.
All in all the proportion of interesting threads is pretty high, whether music or non-music. But I don't think there is any way that breaking up the forum or excluding some types of thread as un-Mudcattian would do anything to increase that proportion. The only way to improve things is thread by thread and post by post.
And that includes not doing things that we know is going to gratuitously irritate other Mudcatters, such as failing to label threads we start in a helpful way, and posting as anonymous GUESTS. As WYSIWYG said, "Can we not do this in love out of free choice, and stop looking at rights?"
There'll always be some pillocks who actually enjoy gratuitously irritating other people, and they'll keep on doing things like that, but there could be fewer than there are at the moment, and that's be a great improvement.