Am I seriously reading a comparison of Waluigi's situation to Pac-Man's situation?
No, just no. Say what you will good or bad about Waluigi, but he didn't change gaming. Pac-Man did.
Pac-Man made gaming mainstream. And not just mainstream, but something of a global obsession. It was such an obsession it that was cool. The game Pac-Man was so mainstream, so global, and so cool that the first major American record holder for Pac-Man got a letter of congratulations from then-U.S. President Ronald Reagan.
Pac-Man additionally is, according to several polls, more recognizable and/or popular than any gaming character, including Mario, Pikachu, and Sonic.
So yeah, Pac-Man's reveal was a big deal. Pac-Man is easily the most well-known newcomer in Smash 4, and it isn't even close.