If the only thing that stops you is not having a C compiler, then you probably don't want to make a SNES game. Writing 65816 is a means to an end, if you want to make a SNES game then you make a SNES game, using the 65816 is just the tool to make it. As koitsu points out you have to be fluent in 65816 to debug and work on the game, once you have crawled and walked in ASM then you can take the taxi that is C for the bits you can. This is still somewhat true today, Being able to read MIPS really helped when developing for the PSP, PS2. Yes it gives you C++ level debugging but sometimes you just get a random crash and being able to look at the ASM to work out what and where was critical. With iOS knowing ARM really really helps as the iOS debugger is rubbish.
Games don't have to be as good as SMW, people don't want SMW they expect DKC3

What might help is making conditions that drop the entry expectations. For example in C64 land we have a 4K crap-tastic game compo, then we have 16K cart compos this drops the concepts and expectations for games, so more get made as people can commit enough time to bash out a 4K game or 2, but to make a 512K cart top of the line game takes 3 years. Maybe a 32K SNES game compo?