We haven't included all consoles for various reasons. We decided to only include consoles that we actually own, so we could take our own photos and screenshots (we wanted captured screenshots for all their pixelly goodness).
We also didn't include a lot of variants, only if we think they really added something to make it worthwhile. For instance, the Famicom, Megadrive, Dreamcast, TurboGrafx and AES/MVS all had versions that were embedded into screens. We didn't feel this made them especially interesting.