Let's be fair here, I wouldn't say Smash is
completely biased against the US - It's just the fact that Sakurai is Japanese, his staff is Japanese, Nintendo is Japanese, and Smash is a Japanese made game. The east having more influence here does make sense.
The US is thrown a bone sometimes. Like you said, Little Mac and Punch-Out!! were much, much more famous in the US than they were in Japan. I believe a similar thing could be said for Duck Hunt and the NES Zapper. Over here, they're highly iconic pieces of retro gaming, partly due to being bundled with the NES, but not so much in Japan. In fact, the Zapper as we all know it wasn't even released there. It had the appearance of a realistic revolver and was literally called just "The Gun".
So naturally, with the NES Zapper basically not being released in Sakurai's home country and his refusal to have realistic firearms in Smash (Snake's moveset was intentionally designed not to use any actual guns), I never expected it to officially make an appearance in a Smash game. Then Duck Hunt's trailer proved me wrong:
As well as Sakurai's comment on one of the pic of the days: "The object being held is called an NES Zapper. This is an accessory which was released for the NES outside of Japan." So he's not completely oblivious to the west.