People in this thread complain about 8/24 bit colors, but how difficult would it be to have terminal emulator simply map 8/24 bit colors to the 16 ANSI color palette? Shouldn't that resolve most of the concerns?
The 16-color palette is pretty limited so even for text that would be readable with full color, you can end up with either invisible text (black on black, for example) or really ugly and glaring (red on blue).
Mapping from 24-bit color to the 256 color cube is pretty reasonable though, since the colors are close enough that you would have a hard time reading them in the first place.