http://www.mtv.com/news/2148918/joss-whedon-loki-avengers-age-of-ultron/?utm=share_twitter
Joss explains why Loki was cut from AoU:
Joss explains why Loki was cut from AoU:
We did shoot something, but it didnt play, he said. The movie has so much. Its so filled. We didnt want it to feel overstuffed. I really wanted to have Loki in it, but I understood the decision that there were now too many voices in the chorus.