Does it honestly matter. If someone chooses to use pink or blue for their thread then that's their choice. No one else's. This forum is not run by communists.
Admittedly some are harder to read than others but if people can't read a persons thread because of colour and they get no replies then that's a mistake they will learn from.
Amen! If it truly wasn't allowed / thought appropriate / was such a widespread issue on the forums, then GG could easily just change the message options so that you couldn't change text colour... it's not that prevalent an issue, plus as has been said, if you can't read something because it's in a funny colour, just highlight theoffending word / words and Voila!