It is an intriguing update in the character’s mythology, especially following Rosemary Harris’ ripped-from-the-pages depiction in Sam Raimi’s Spider-Man trilogy and the darker hair color being the biggest difference of Sally Field’s iteration in The Amazing Spider-Man films.
However, no one is going to fight any reason to have Marisa Tomei on the screen, so it is no sweat of off any Spidey purist’s back.
Traditionally, Aunt May is an elderly woman of, at least, 65 years with gray hair often put into a ponytail and clothes that you have probably seen your grandmother wear, while the MCU reimagines her in her early 50s with long, free-flowing black hair who has been known to sport tank tops or T-shirts from time to time.