In the previous installments of Captain America, Steve Roger's (Chris Evans) morality was never questioned even though he was defying orders (especially if he was defying orders). He indisputably did the right thing by rescuing Hydra POWs, one of which was his best and closest friend Bucky Barnes (Sebastian Stan). He also did the right thing by taking down SHIELD and Hydra in one fell swoop. Here, he is the crux in the split of The Avengers, not because he rejects the Sokovia Accords, but because he wants to protect Bucky from being framed. It is perhaps the first time Steve's morality is called into question. And it should have been done better.
For two movies, there have only been the barest hints of a larger universe within the MCU films, easter eggs if you will, mostly in the special scenes after the credits that Marvel made standard after The Incredible Hulk, where there is no end credit scene. (Or if there is, it was moved to the front of the credits for the DVD version I saw). That comes to an end in Iron Man 2.