While talking with The Wrap, Kevin Feige revealed that a popular rumor/spoiler dictated the end of Avengers: Age of Ultron.
The end of Avengers: Age of Ultron was actually changed due to a pretty big internet scoop that turned out to not be true in the end.
Marvel head honcho Kevin Feige has recently revealed that Avengers: Age of Ultron wasn’t actually going to end that way and that we were going to get a clearer picture of where Bruce Banner was heading.
As to why the MCU didn’t follow through with the Planet Hulk movie, Kevin Feige says that they wanted to do something different with Thor.