One thing to note is that the button colors used match the Japanese and PAL SNES, but not the North American SNES.Now the thing is, save for the DreamCast, every console in North America that has used multi-colored face buttons has used blue (N64, PlayStation) or green (GameCube, Xbox) for their primary button.
Not only that, but red has at most been used for a secondary button (O on PlayStation, B on GameCube and Xbox, Start on N64), never as a primary button (except DreamCast).Even yellow hasn’t been used for primary or secondary buttons, only for third-tier buttons – even on DreamCast! (C on N64, X on DreamCast, Y on Xbox).
Interestingly enough though, in Japan, the red O button is used as the primary button on PlayStation while the blue X is used as the secondary button. This matches the DreamCast perfectly and also matches the red A button on the PAL and Japanese SNES.
OK, that is more information I ever knew about button colors!