Children, young adults, parent, grandparents will relate to Peter Parker as Spider-Man because that's who has been Spider-Man for their entire lives. Interest waned in the ASM movies because they stunk, that's all really. Look at the pre-Nolan Batman movies. They were horrible and there wasn't even a thought of having someone other than Bruce Wayne as Batman in the later films.
I hope UF4 keeps going up, I'm still finding them in the wild for cover price or less
Children, not grandparents, are the demographic Disney and Marvel care about and want to cultivate. Miles Morales is already in the cartoon series, he is popular with kids, and gaining more and more momentum. For all intents and purposes Peter Parker the comic book character is a thirty something married guy, his appeal as an awkward teenager who gained superpowers has been diluted over the years, and the movies have proved that this trope is well and truly played out. Bruce Wayne & Clark Kent are timeless simply because they started their comic lives as fully fledged adults. Peter Parker has been forced to grow into adulthood in a span of decades in comic books which has been an awkward process at times.
Miles is a fresh take on a tired character. The Spider-Man costume is the draw here, not what the name of the character is beneath the hood.