I think the main point is that the split view is now the default position when anybody visits the site.
I am aware thay it is possible to reset your personal view to mix the two, but let's face it, most of us can't be bothered to do so. I sometimes think of trying the switch, but by the time I have finished reading whichever current thread or list of threads, I have forgotten my intention. I also cannot remember instructions for how to do it by the time I revisit the site.
I am sure that I am not the only one.
My personal opinion is that I would prefer the original mix as default but with the option of separating categories if a viewer is particularly bothered.
I would also be in favour of sub categories within BS. Something to enable me to find threads which are "social" - e.g. who is attending festivals/events, "political US/UK" so that I can avoid them, "fiction/imagination" Mudcat Tavern/Stories/Donuel's artwork, "humour" blowed if I can think what would go there....

Quack!
Geoff.