I use most of the 12 colors prepared in the new color palette for track/bus strips because they already look nice on them, but they don't look very beautiful on clips so I use colors I edited and saved in the color palette that opens by clicking the "Other" button. I change clip background colors a lot, and having to click 4 times in total just to change one clip background color has been a bit of a pain for me. It would be nice if the first palette could add a custom color area like this:
 

 

I think this (or something very similar) had been requested before, but I voted again because I like the idea.   As you mentioned the default colors work well, but slight variations are welcome, particularly if more accessible.