We don't have any problems with your feedback. In fact, we appreciate your effort to make the product better, and I'm sure other community members will agree. Although we might have different opinions on some of the features or functionality, the feedback from other users will be the decisive factor.
Additionally, there are numerous scenarios for each module, and we cannot support all of them out of the box. The advantage of MonoX is that allows easy customization in such cases, but you should not expect that everything will be achievable via simple point and click interface - some coding is required.
As for your points,
1) blog authors are already able to do all of that.
3) news and blogs are entirely different concepts. In the news sections, separate user roles can manage their own news categories without being able to modify other categories.
4) by default, admin can allow multiple users to be editors of any of the blogs in the system. These editors have a complete control over "thier" blogs. Other scenarios - where each user gets its own blog while registering, or where a blog editor cannot manage other people's posts, or wahtever - are possible, and we implemented them in various custom projects. However, they require some amount of custom code.
5) some users do think it is safe for their scenarios, others don't.
6) it again depends on the scenario. The majority of our users want their categories and tag cloud to be independent of other users' blogs. In such cases, when I visit the blog of the user A, I want to see only his categories and tags. Otherwise the end user could easily be confused by thousands of categories and tags that do not have anything to do with user A blog. So, that is the scenarios supported out of the box. It is not diffilcult to support "your" scenario in code (it is actually easier to support it than our default scenario), but I cannot remember that we ever had such request.