The reason behind that is simple.
Stardock doesn't want the user to create new mouse cursor anymore.
first of all, in previous version, they used the .CurXpTheme format cursor wich was a .zip file renamed .CurXpTheme. You could extract file from them, modify them and create your own theme based on the work of someone else. This created copyright issue they deemed to fix.
Stardock created the .CursorFx file format wich is propriatary (own by them) and they do not want to give up "how" to make a .CursorFx file. Meaning, nobody can export to that file format except them. Wich in turn might kill the business.
Then, their own "editor" only allow to import PNG file wich is an Image format.
PNG file CANNOT be animated. However, it exist a format called aPNG wich *IS* the animated form of an animated PNG (https://en.wikipedia.org/wiki/APNG) (there exist only a *few* editor able to create APNG files
But the Stardock editor for the cursor doesn't allow to import APNG, furthermore, it doesn't seem to support it.
Meaning... they don't want us to create .CursorFx file and they don't allow us to even create animation for the cursor we want to create
and their Editor is very limited (or broken) Try to open an existing Cursor Theme, remove a cursor inside of it, save it and put it in place, reboot and you'll see that the visual change you made is not taken into consideration beside the "remark" you can update.
Just my 2 cents but in order to make the business of customization grow up, they should make the CursorFx format open source.
YES the work need to be copyright and respect and due diligence should be given to thoses creating original ART. Nevertheless, because of the current business model, content creator are very limited in what they can do.
Same goes for WindowsBlinds. in order to edit or create a theme, you need to use SkinStudio. A program nowhere to be found and all link extinct. when you try to download it, it bring you back to the download page of WindowsBlinds
and every forum that talk about this got erased.
so... go ahead... erase me.