Provide the «New Category» dialog with an ability to suppress an auto-creation of the category topic.
I don’t understand this request. Could you please expand with mockups?
My take when I saw this earlier was that it’s a “please make it possible to do something that shouldn’t be done as a Core feature”. i.e. create a category without an “about this category” topic.
Upon further thought, I think a better approach would be to identify what the problem(s) might be with the way things are now.