Hi Gary, thank you.
Yes, I considered raising a request for this.
I am really liking Tiki so far, which would make contributing with the code worthwhile down the road. That would imply picking up some PHP skills but most fundamentally understand Tiki's internal structure.
Since at the moment I am evaluating Tiki, I am getting to know the product as much as I can - in the meantime I logged a bug related to phpBB authentication no longer appearing to work in Tiki. I think solving existing bugs should take precedence over new feature requests.
The reason for my post above is to explain why I believe there's value in improving the Forum section with sub-forums and see what the community's long-time residents such as yourself think.
Thanks for the support, much appreciated.