I’m not sure if you’d call this a feature request, but in a previous version of aseprite there was a bug that I actually found quite useful.
The bug was that Scroll+Alt in the color picker didn’t change the selected color. Instead, it gave the current slot the color of the slot next to it.
I used that to make color palettes, as it allowed you to easily pick new colors based on colors you already had.
Maybe there’s better ways to do this that I don’t know about, but so far I haven’t found anything that works.