This is a very old subject, many threads have been created by players complained about the intense red of the KDF UI, myself included, as well as some complaining about the bright blue of the FED UI and it seems those complaints have gone unheard.

For myself, even being able to just turn off the frames and borders on the UI leaving only the active elements would be an improvement.

I've taken to shrinking the scale of the UI to a minimal but still viewable size to compensate.

I certainly wouldn't mind if at some point they build in the ability to use user designed mods for the UI elements.