This makes it near impossible to properly look up information.
You may use the forum search or google search with "site:bitcointalk.org".
Each subforum should allow users to create subforums.
Not sure if I understand your idea correctly. Do you mean any users can create subforums as they want?
If that is the case, I am afraid it could be and would be abused to create lots of craps...
I think the search is limited and there should be more granular presentation of sub-forums. Maybe not let everyone create but make it easier to create them and/or create more of them.
Each pool, hardware vendor, sub-type should have a sub-forum. as it is now there is one main then one level down.