Hi Luca, I think it is inappropriate that you put your personal preferences over usability in general. It is unreasonable to set a font color without taking the background color into account.
My request is to go with upstream's default, giving a readable output in general. If a user prefers to have colors, he is still free to configure iproute2 in his private environment accordingly. Upstream follows this good practice, so should Debian. Regards Harri