I think an RGB value for /echo is a good idea for a simple coloured info line or something, but that's about it, that's very limited for the matter at hand...
I don't think the human eye would really be able to tell the difference between 0 to 15 on the RGB scale (I can't anyway), so it could still accept those values as mIRC colours, and people could use 16 for black.
I'm not sure I understood what you're talking about.
Which values are "those"?
Edit: nevermind, I've read the first post on this thread again, now this makes sense.