The Russos wanted to make a sequel to TWS that focused on Cap and Bucky - but Then Snyder announced that the MOS Sequel would be a "Batman vs. Superman" movie.
You have Feige to thank for Civil Skirmish and its absurd jerry-rigged conflict between the heroes.
According to the Russos they originally pitched adapting Civil War but were shot down by Feige. Then when BvS was announced he relented and allowed them to make the film that they wanted.