I don't think the SNES actually had anything in its design that made extensibility easier on it than the Genesis. This and the Super FX - not to mention the Se

I don't think the SNES actually had anything in its design that made extensibility easier on it than the Genesis. This and the Super FX - not to mention the Sega CD or the Sega SVP used in Virtua Racing - etc. all just uploaded video data via the cartridge port and blitted it to the screen console-side. The only reason the 32X needed to do the weird video interception kludge was to get around the Genesis' poor colour depth, and exactly the same thing would be needed if you wanted to do that on the SNES (the SNES had less of a need for that, but...)