It seems like LibreOffice developers have their heads in the clouds. Shiny new start screen, formula GPU acceleation, borders around characters, sidebar, while a very basic feature, color selection, is severely broken and hard to use.
I can understand that this can be frustrating, but what kind of answer do you expect here? My short go at it would be: because no-one changed it. Did you file a bug report/feature request?
But why no one changed it? This is a glaring, extremely obvious usability issue, and I can’t imagine this being hard to fix (at least add “Custom Color” button into the palette), unless the GUI code is very bad, yet it was ignored in favour of less important things all the way since the beginning.
Also, there is a bug for this, and I don’t think that writing another one will help, since this issue is so obvious that I’m starting to doubt that LibreOffice developers actually use it themselves.
@lamefun - Thanks for your contribution on this site but even more for writing all the details in “Jef’s blog”. I agree to what is written there. May I ask you to file an enhancement request and publish the link here so other people can add there comments to your enhancement request?
This same question has been asked, in far greater detail, here.