Look at this:
You see that little chink in the Winter Soldier's goggles, that makes him take off his eyewear
and show us those baby blues? Black Widow did that. Let me repeat that:
Black Widow, shooting from under an underpass to the top level of a freeway, shot the eye…
The only argument I can see against a Black Widow movie is this: She’s too busy keeping ALL THE OTHER HEROS ALIVE, and doesn’t have time for a solo gig. Okay, I’m only judging by Iron Man 2, Avengers, and Winter Soldier, but think about how those movies would have ended if she’d been off doing her own thing (not that Manhattan would be a big loss). Hell, she couldn’t even finish one little interrogation without Coulson calling.