The anwser is actually quite simple… And has been the same all these years.
Uncheck “Prefix all forum content with the Forum Root slug (Recommended)” under Settings > Forums > Forum Root Slug.
This gets rid of the /forums/ part and leaves you with the usual /forum and /topic slugs which are prefixed to forums and topics respectively.
The reason for this “sectioning off forums” is to prevent conflicts with pages. Which it does pretty well, and due to the simpleness of the solution, will probably not be “fixed”. You could submit a ticket on trac, argue your case and submit patches if you want it changed though.
