The notion that there are properties that "don't call for" minority characters is expressly the problem. One that Marvel doesn't appear to agree with, thankfully.
These stories are products of the 60's. Entertainment was certainly less diverse and inclusive at the time; if a minority character appeared they were either a token or a caricature, usually both. Part of adapting these stories for the screen is adapting them for a modern audience - none of these comics, if written for the first time today, would feature all-white casts, and rarely do you see a piece of media that doesn't prominently feature characters of both genders.
Originally Posted by I'm Venom
Let's make them female just to get that diversity train going, eh?
Sure, why not?