This definitely seems like a sensible starting option to generate 256 colours from a custom set of 8 (and then let the really pedantic users fiddle with the ext

This definitely seems like a sensible starting option to generate 256 colours from a custom set of 8 (and then let the really pedantic users fiddle with the extended set). I would presume for "standard" themes these values would be pregenerated and adjusted slightly if needed.