Aside from the fact that he almost broke all box office records with The Avengers, Avengers: Age of Ultron - though not having had quite the same impact as the first one - has also been able to hit the 1 billion mark, and it's not even opened in China yet...
I want to talk about the director's creative vision. For those of you who don't know, Joss Whedon has been influencing us and our children for years. He wrote the screenplay for the original Toy Story film, which is quite possibly the best thing about the movie. One could argue that the original Buffy The Vampire Slayer was a failure, but you have to remember that at that point Joss Whedon did not have the clout to say "this is my creation and this is how it should be."
Warner Execs and overrated actors all put in their two cents on what the movie should look like, and thus we were left with what we got. I remember an interview with Joss where he was talking about his feelings on the movie Buffy vs. the TV Buffy, and he had mentioned that the only character that was represented accurately, at least in the way he had envisioned it, was Amilyn - the character portrayed by Paul Reubens - who in my mind was also one of the best parts of the movie.
Getting back to Joss Whedon's vision, you really only have to look at the TV series of Buffy. It paved the way for many of the shows on TV today, showing that a Drama/Action show could incorporate a comedic element while also tackling serious issues such as bullying, domestic abuse, and substance abuse, not to mention things like gender equality and tolerance. Buffy itself was also the first TV show to show a same sex kiss on prime time television, much in the same way that Star Trek was the first show to feature an interracial kiss.
His creative vision knows no bounds, and so I challenge you to go back and re-watch Buffy. You'll quickly notice that the shows that seemed like fillers in comparison to the story arc for the whole season, were in fact lynchpins. Season 4, episode 10 "Hush" for example, in which 80% of the episode saw the entire cast lose the ability to speak, was a central turning point for the whole season: Riley learns that Buffy is the slayer and Buffy learns that he is part of the initiative.
My two favorite episodes of Buffy were Season 5 episode 19 "The Body," and Season 6's "Once More With Feeling." The latter pretty much paved the way for Glee, but was also just a completely fantastic hour of TV, I mean, who knew Anthony Head had a voice like that. "The Body" is a favorite simply because when you are watching TV subconsciously, the background music in the show denotes how you should be feeling at a given moment. "The Body" had no background music for the entire episode, and in an episode where a much loved character dies we were left with the actors having to wholly bear the burden of conveying the feeling to us. It was genius and quite possibly one of my top 10 favorite TV episodes of all time.
Joss's influence can bee seen in shows all over TV, shows such as Castle, Supernatural, and obviously Agents of S.H.I.E.L.D. But he has also launched the careers of some of the most beloved actors and actresses of today. Here is just a small list of actors and actresses that were relatively unknown before joining the Whedonverse (not including the MCU): Alan Tudyk, Nathan Fillion, Eliza Dushku, Allison Hannigan, David Boreanaz, Felicia Day, Chiwitel Ejiofor, James Marsters and Amy Acker. Yes, I realize some of these names many people might not know, but IMDB them and you will be surprised as to some of the things they are or have been in.
With the following that Joss has amassed from TV alone, not to mention the creative genius giving us gems like The Cabin in The Woods and Dr. Horrible's Sing Along Blog, I feel that all of the controversy surrounding Joss departing from the MCU is completely unnecessary. He loves to create and he wants to go back to utilizing his own creative vision, instead of creating his interpretation of someone else's vision. After the billions he has made at the box office I believe he has deserved the right to a break.