Wii's specs weren't a problem for either first or third party support. Nintendo were clearly comfortable building games to that spec, while games like Modern Warfare 3, Rayman Origins, de Blob 2, Conduit 2, etc in 2011 showed third parties could also easily make games for it if they wanted. But why would they when Nintendo themselves stopped properly supporting the platform?
Wii's specs had nothing to do with Nintendo moving on prematurely.
SNES was well supported up until its replacement and even got significant games after that like Donkey Kong Country 3 and Kirby's Dreamland 3.
I know that it got DKC3, but it was so-so, a sequel to a sequel to an existing game, and it was just one late game. I forgot about Kirby's Dreamland 3, though again I don't consider that big support in end of lifecycle. Still, I'm aware that the SNES was better than the other two examples. When compared against Game Boy and PS2, it's a no contest and that was my point.