The packages kde-baseapps, kde-plasma-desktop, and kde-standard are meta-packages, designed solely to depend on a set of individual packages. Such as what makes up a complete desktop environment and set of applications (kde-standard), a minimal core set (kde-plasma-desktop), or even a subsection of components (kde-baseapps).
These meta-packages don’t include software, libraries, or files themselves. When you want to remove something that is included in one of these lists, it has to be removed as well as the app. Otherwise they will cause that app to be reinstalled the next time there is an update. It is OK for these to be removed, though it is usually a good idea to make sure that they are present when performing a distribution upgrade. Re-installing the top-level kde-standard would take care of that here., iirc.
As to Kwrite also being removed, that is because both Kate and Kwrite are two different forms of the same application, and all share the same bits, so they have set things to depend on each other here.
In your case here, kate is a core part of the metapackage kde-baseapps, which is required by kde-plasma-desktop, which is required by kde-standard. Confusing, yes. But so is accounting, which is sort of what I compare it to.