Before I retired one of roles was managing an internal tech support "help desk" and knowledge management for a technical domain in a large international corporation. The key to core knowledge management system was classification and verification, this made searching and browsing very easy. Verification and a user feedback system meant the content was reliable and frequently reviewed.
We also had builtin boards which did not have classification or verification, this is the case on a forum such as this. We could harvest the best from the builtin boards and convert into content for the the KM system. This requires a work and staff allocated to the task.
To some extent the chaos inherent in forums and bulletin boards is their strength, people are more open in such an environment. The down side is chaos, like here where the sub-forum system is often bypassed and posts end up in the "wrong" sub-forum. If a moderator moves a post people often get upset.
Introducing classifications may help in finding information but the required manpower and costs would be prohibitive.
I think the the introduction of more sub-forums seems like a good idea but in practice it would only be effective if strictly moderated, which in turn would discourage participation. Catch 22.