There are not 1000+ bugs. The majority of the issues filed for the project are feature requests and suggestions, and there is a lot of healthy discussion that happens inside of those issues.
No need to repeat, however, feedback that is actionable is the kind that is specific and so it’s always good to include a specific example about your own experience if possible. Your question about how the default state for panels like Categories and Tags is a great example!
> Since the Categories and Tags of post are important, why they are closed by default?
I can’t say for sure why, but my guess is that it’s for visibility perhaps? In any case, I tested and I noticed that whether the document settings panels such as Categories and Tags are open by default is a sticky setting. That means once you open one of the panels, it will be open by default the next time you open a post for editing. In my testing, the sticky setting for whether panels are open or closed is saved in the browser session, not in user settings, and that means the setting could timeout or you may have to re-open a previously opened panel if you switch to another browser or clear browser cookies.