The thing is, Peter Parker is such a neutral character, his skin color makes no difference.
Perhaps not to you, but for a young child of color lacking in pop culture role models and positives influences, it could make a big difference.
I'm not of the mind that movies should generally be made with some kind of social justice agenda--really!!
--but if a black guy got cast as Peter Parker or something like that, I wouldn't really bat an eye and would rather consider it a positive step.