It was possible to make great music on the Genesis but I see that as more of an acception rather than the norm.
Which shows you didn't play Genesis a lot. Or SNES.
Because on both console, average was the norm, and great soundtracks exist on both, with no real winner.
I think Castlevania: Bloodlines has one of the best soundtracks of any game for any system.
Of course it's debatable, but there was plenty of MD games with soundtracks I still remember. SoR 1, Revenge of Shinobi, Sonic, Phantasy Star 2 & 3, MUSHA Aleste to name a few. You can even find games where the MD version has a better soundtrack than its SNES counterpart (Street Fighter 2 for example, even if I agree the voices are terrible).
The sound fx are of course where the Genesis fails most miserably. The ugly, limited palettes and the poor sound compared to the SNES have always prevented me from properly warming up to the Genesis.
While it's really true for the palettes (why on Earth didn't Sega design the VDP to use different palettes for sprites and backgrounds? It would have cost nothing more than 128 bytes in CRAM), it's definitely not for sound.
And as you say later, many games succeed in avoiding the palette problem (due to talented artists).
Considering the hardware is some years older, I really think the MD compares very well. The Blast Processing thing is commercial bullshit : the 68000 was noothing exceptionnal at that time. That's the SNES which invented Crap Processing rather