Hmmm that is an interesting situation that I feel like Geno is placed on this pedestal beside Ridley and King K Rool for characters fans have wanted for decades, but at the end of the day I feel like more people on here would be dissapointed of Skull Kids deconfirm. I for one would be surprised Geno didn't make it in but wouldn't care, Skull Kid I actually want. And to go with that I feel most casual players would be wayyyy more excited for Skull Kid since they might actually recognize him.
Alright now I'll be pissed of Geno gets in but not Skull Kid lol.
More people would be disappointed because more people have experienced Majora's Mask.
The thing about nostalgia is it brings about bandwagoners who want to feel like they're "part of the club". I've encountered it so many times when an old game/cartoon/movie/comic/whatever is brought up, and someone gets extremely excited, saying, "OH, MAN, ME TOO," only to reveal shortly after that that he really doesn't know much about the topic-- or in many cases, hasn't ever played the game in question.
Super Mario RPG was on the SNES in 1996 and sold an impressive 2 million copies. But Majora's Mask released in 2000, sold nearly 3.5 million copies, and then was rereleased on the 3DS recently to the tune of 2 million
more copies. Skull Kid has also been prominent in other ways, such as getting his own Nintendo-licensed figure, being a playable character in Hyrule Warriors, etc. while Geno, to my knowledge, has been more or less relegated to history, and relies on people who actually remember his game from 22 years ago, while the character Skull Kid is not only more recent, but has also been reacquainted with newer fans multiple times.
The short of it: the younger fans know who Skull Kid is, and pretend to know who Geno is.