Falcon taking on the mantle of Cap was a bad call because it literally had not been foreshadowed in any of the million MCU movies. Bucky being the new cap would have absolutely worked and it would have continued his redemption arc. Like Steve he is a man out of time with old fashioned ideals about patriotism and America, only he has to reconcile with the dark side of international politics that he was very much an unwitting part of as the winter soldier. He has enhanced powers like Cap so no one is going to question whether he can catch a vibration shield or take a punch from a super powered villian.
Also it would have been infinitely more interesting to have tortured soul Bucky Cap trying to make amends whilst the public at large reject him despite the good he is doing. They could have brought in modern day politics by having fake news angles showing Bucky Cap in a negative light etc. Falcon should have stayed as Falcon as his comic foil as those two had such good comedic chemistry under better writers. You could have had Falcon exploring the civil rights angle if you wanted to, only handle the subject material more sensitively.
i stand by my general feeling in the theatre that Falcon Cap felt like an after thought with more than a hint of pandering. Falcon never needed to be Cap, he was already a really interesting character. Bucky needed to be Cap, now he is just the same old winter soldier only he is working for the US doing the same old espionage stuff that he did for Russia/ hydra - why would the character allow himself to he treated like that?
