I mean Claude literally does not have eyeballs, it cannot feel discomfort, it does not need to squint, it cannot be annoyed by low contrast, and it cannot desire something better, it will not seek to improve this unprompted as a human would to "scratch its own itch".
For that to matter, the user has to bother setting it up, but the user is too lazy to do that, the user doesn't want to do anything at all, which is why they asked Claude to do it
darkreader.org helps.