More screentime doesn't always correspond to plot importance, precisely. Falcon and BP have roughly the same amount of screentime, but while T'Challa has his own arc and character trajectory, Falcon is only sort of there. BW was the one being whose court hearing we've seen, and the one for whom the leaking of SHIELD's secrets was supposed to be a huge character beat. TWS was less obvious about it, but the same mentality produced both. Steve who is romantically inexperienced? Who kept hearing Natasha pestering him to date random girls? Not a surprise, really. Or perhaps, again, it wasn't Whedon's responsibility to tie up the Russo's loose ends. It wasn't his job to develop Sharon when the Russos neglected to reveal her last name, and if he didn't feel like expounding on those consequences, maybe the Russos shouldn't have left that thread dangling.