This would be a nice addition: The ability to override a variable declaration per page to bring theming power to the next level.
I have a variable accent-color set to #123456 on my site globally
On a certain campaign landing page, I want to set accent-color to #456789 instead, eg. to make that campaign stand out
Instead of having to change all instances of accent-color to some new variable else on that page, I could just override accent-color in one place on that page and boom.
Simple yet powerful.