Originally posted by: Shiru
It is way more difficult to develop for SNES, both code-wise, because the system is complex and powerful, while available tools lacking, underdeveloped and/or unreliable, and especially content-wise, because one person have much more chances to create content (graphics, sound) that will look good/acceptable for the NES, rather than for the SNES. Amount of content in SNES games is also larger, and expectations much higher for SNES games.
The other corrolary to that, I'd suspect, is that many who might make a game on the scope of where expectations would be for an SNES (graphic detail and variety, overall game size, etc) might just divert those efforts into something with more commercial viability as a PC/modern-console digital release.
Not saying that it applies to everybody, but my personal feeling would be that there are a couple of plateaus of effort, and at each one I'd have different tiers of commercial aspiration.