Seems like I didn’t get your point, but thanks for elaborating 
I thought you mean if you don’t set the applied default class as a virtual block class.
What about a dedicated default style? Maybe on top of the list (1st item)?
This would target the block class directly:
These could be prefilled to get us started quickly.
Everyone could set up things to their own requirements.
That approach would also address this.
Complete freedom without the need of overriding stuff (is the max-width hard-coded btw.?).
Currently, there is no real default, since the last item in the list always takes over priority when there is no class applied.