To be fair, Smash already has a lot of the most recognizable characters in it. When you already have Mario, Pikachu, and Sonic it is hard to get a more recognizable face. Obviously there are big video game characters left out, but they are frequently discussed in this topic.
Also, I don't think comparing to non video game additions holds any weight. We know that, up to this point, Sakurai isn't willing to add characters from other mediums. Sure we can say that adding Winston Churchill would have more recognition than Akira Howard, but it isn't possible so who cares?