Seems the ability for props to change CSS variables is necassery.
For example, for allowing the user to set the obvious gaps and margins for manipulating the design to their liking, and whatever else the dev can imagine.
Every basic Wix element has this basic customizability.
So other than being basic, it's what Wix got users used to.
And the lack of this basic customizability creates bad UX and reduce the value of our apps.