I think that is at least misleading, if not inaccurate. They may not have been "designed" in the sense of a graphic designer choosing the most pleasing or user-

I think that is at least misleading, if not inaccurate. They may not have been "designed" in the sense of a graphic designer choosing the most pleasing or user-friendly colours, but there was logic behind the choices. They're the eight permutations (three primary colours (red, green, and blue), three secondary colours (yellow, cyan, and magenta), black, and white) that you get by setting each of the three RGB channels to either zero or maximum. It's not great for terminal text on a black background, but it's better than the CGA palette, IMO.