It has been working for decades and I would rather have it keep working for decades to come.

What would be optimal is semantic _styles_ (not colors):

- The developer marks the string "XXX" as an error message without even trying to style it.

- The platform/user agent/terminal/whatever displays the string in the default style for "error".

- The user can adjust the theme of their platform/user agent/terminal/whatever to fit their needs/wants.