In an alternate universe, where SEGA put a cowbell into the Genesis:
My point being that the SNES, seen as a developers canvas to express their vision of a game, is far better suited. They are both heavily compromised machines compared by today's standards, but it wasn't all a retro-laugh at the time. The SNES's ability to create fitting background music for about every game scenario with an interface understandable to musicians without engineering or programming experience, is most probably the reason there's so little bad music on the system.
Compare that to the extensive knowledge of the hardware needed by the composer to create music matching the genesis's sound chips. The process is just wrong from the beginning. Creating music should be creative task, not an engineering task and the SNES was far ahead of the genesis in that regard.
This thread also ignores that most examples of good genesis music use the PCM channel, which leaves the actual game to FM-ploings and boings as SFX.
But a cowbell isn't known for its flexibility... which is exactly why you used it as a substitute to make the statement sound absurd.
The skills required to utilise a device isn't a defining factor of how good it is. It can definitely increase the average output, but something isn't bad simply because most people have no clue how to use it. If the Genesis were released today, then far more musicians would be able to achieve better results, as the proliferation of software studios, VSTs and the like would mean that people would be more exposed to the concepts of working with a synth, whilst at the time sound engineering was part of few people's skillsets.
I would agree that the SNES for the time was better suited for the industry and what it required... but I also see it as the worse actual device when it comes to audio. The Genesis has continued to sound better as time has passed and the average person's audio equipment has improved. The SNES however, removed from the crappy mono TV speakers that most people would have connected it to at the time, now reveals clearly all that it lacks in clarity and range. Emulation has somewhat disguised this, as people will rarely ever actually hear a SNES or a Genesis today, but t Genesis has a notably better output, where the music is still sufficient as it, whereas you'd basically have to remaster anything a SNES put out, to make it even remotely acceptable quality today.