Yeah the original intention was to make the admin dashboard options a simplified way to set colors, basically an “easy mode.” I agree that it is limiting and contrast isn’t great for some color combinations.
The good news is that remote themes can override all the automatically generated colors, see Override values for auto-generated color variables
We’ve also been taking a closer look at how our colors work lately, with the hopes of making it easier to work with color schemes and light/dark modes for both admins and users, so hopefully we can make some helpful refinements.