Certainly would add more variations to life. The colour blind will become the new dislexics.
Imagine the excitiment of interior designers.
'What does this house say about you?'
I've always believed that we should be taught one universal sign language as kids. Obviously there are certain signs that are global (and not necessarily diplomatic) but to be able to communicate too any people would be a boon.
as ankhsy says men would be very unsubtle as most of us can go red blue green etc...but when it comes to fuschia, marron, emerald etc..language subtlety would be totally lost on us!!
Centurion Parmenion LASCIATE OGNE SPERANZA, VOI CH'INTRATE