Why do people love Marvel movies?
The main reason which attracts audience to movie theaters is that people know that Marvel Cinematic Universe has the WINNING RECIPE.
Marvel Cinematic Universe has been making the right choices, picking (sometimes not the best, but.) the right scripts, choosing the most suitable directors right from Jon Favreau to Ryan Coogler, not to miss the Jos Whedon era during the inception of Avengers characters and the reason director-duo, the Russo brothers.
The main thing that worked for the MCU is that they have the best gunslinger as the captain of the ship, Mr. Kevin Feige.
The common attribute that all the makers have in the Marvel Productions is that most of them (maybe all of them by now) are avid comic readers and Marvel fans. Even if they aren't, Disney has had this policy to make each of their employees at Disneyland wear “Goof” costume or some of the Disney costumes on workday (I am not sure if this is still going on) just to grab the attention of guests. This might also have proved the Marvel Productions to make their technical staff read comics and get the plot clear. Ideologies such as this are what bring success in keeping the ship and the crew happy and interested in their work. Thus, giving the results which most of the other productions can only desire.
Also, these movies bring out something in people (such as me) that they desire apart from the usual “dishoom-dishoom” movies.
People who already are/were comic readers will have the curiosity of how their favorite comic characters come out to be in a live action and will be attracted to the comic genre out of interest.
People who don't follow comic lines watch the Marvel movies because they are the only kind of movies these days which provide hope to be entertained along with their children or their nerd friends.
But the common expression I notice on each of the faces I went to these movies with is that we get to relive our childhood and get to cheer some fictitious characters we once used to worship in the form of Shaktimaan, Superman, Spiderman, Batman etc.
Learn more about the characters, movies and upcoming releases at Marvel.com