> Firstly it solves the age-old problem of low-contrast text, like when you `ls` a broken symlink and the red background colour is too near your current theme's foreground colour.

That’s already a solved problem. You use a terminal theme that produces high contrast against all the 16 terminal colours.

Plenty of good themes exist.

The bigger problem, in my opinion, is software that uses 8 bit or 16 bit colour ANSI codes and thus overrides your terminals theme. Personally I consider this rude behaviour but I know there is a subset of HN that disagrees with me here.