Here is the problem dude. You are arguing about which characters people want, not which characters are most probable. Wanting a character does not guarantee inclusion. A lowly employee at Sony actually said in an interview that Square was very, very hard to negotiate with and... do you see any Square characters at Playstation Allstars?
Sakurai has stated many times how hard it was to get Sonic in, he wasn't even involved in Sonic's moveset and had Sega do it, but he still had to balance it, which makes it harder yet. But here we have an IP which you have to do very minimal negotiations for and you have to do 0 checkups with the company or wait for that company to give you the green light to introduce an specific thing from the IP into your game as that company already knows everything thats happening on your game because they are developing it.
It is not all about popularity, other factors mind. And Pac-Man is just popular and famous enough that his "hassle-free" status catapults him into the realm of possible characters for Smash 4, even puts him at the top of the third party list in my opinion,
It isn't about what people want only, its about whats possible and what is achievable.