and here's this article about Netflix Matt not being a redhead.
http://birthmoviesdeath.com/2014/08/04/outrage-matt-murdock-not-a-ginger-in-netflixs-daredevil
don't know if it's being serious or a bit tongue in cheek.
but I did note this part:
"Will anybody care that Matt Murdock isn't a redhead? It's a weird question, but this is nerdtown - people get really tweaked out about physical discrepencies between actors and characters. You couldn't have a Mary Jane Watson who wasn't a redhead, despite her hair color having no bearing on her character."
and yet. that's exactly what we seem to be getting in Homecoming, amongst other changes.
unlike Matt, who has a costumed alter ego, MJ does not have such an alter ego. Her civilian look is her look. and her red hair is the most iconic, visually distinct part of that look.
take that away, and you've already taken away a unique, distinguishable feature. Just look at that comic panel above where she's blonde. There, she looks like another blonde female - she looks like Gwen more than MJ.
change her look further by making her plain and frumpy looking, and you've altered the character even more.
and if that's not enough, you then change her personality to be almost the complete opposite.
oh, and if even that's not enough, you change her name to something else, or give her some contrived backstory where she uses a different name for most of the film.
at that point, she's essentially a whole different character. what's the point of even using the character if she looks and acts nothing like how the character should?