Themes "changelog"

It’s strange that there are complete guidelines for plugin submission that require a readme.text file with a section for changelog and there aren’t the same guideline for themes en the official repository.

It’s frightening to update any theme with no information about the changes that you’re going to approve, while with plugins you are plenty informed about what is gonna happen.

I’m truly concerned about this absence of mandatory for themes since they are the face of our sites. And yes, of course, I can make a child theme for my customizations but the problem remains the same: I don’t know what it is gonna happen when I update a theme from the repository.

Why?

Cannot this be changed?