Both Ben Grimm and Steve Rogers grew up in the Lower East Side in the comics, but this was changed to Brooklyn for both of their movies. Is this just a funny coincidence, or is there some reason why Brooklyn is better for movies?

I think it has to do with the way that the passage of time shapes our mental maps of New York City (although the same process happens with all cities). 

Jack Kirby was born at 147 Essex Street – which is just south of Houston, and two blocks away from where the modern Tenement Museum stands – which was at the time a Jewish immigrant neighborhood, and he used his childhood experience to create a background for both Ben Grimm and Steve Rogers. (One can see this most clearly in the case of Ben Grimm and the Yancy Street Gang, where Yancy Street stands in for Delancey Street, which is about a block and a half south of Kirby’s boyhood address.)

However, over time Kirby’s childhood neighborhood changed dramatically: from the 40s to the 60s, Jewish and Eastern European immigrants and their kids moved out and African Americans and Puerto Ricans moved in; then from the 1980s to the early 2000s, gentrification spread from the East Village down to the Lower East Side, as students, artists, and yuppies who were finding the East Village now a bit too expensive went looking for cheaper rents, and brought trendy restaurants and art galleries with them, and by the mid 2000s, development started to shift to luxury condos. The point of this is that in the minds of younger writers, the Lower East Side isn’t a working-class immigrant neighorhood, because working-class people can’t afford to live there any more.

However, Brooklyn still has something of a more working-class cachet to it, especially in the minds of the broader movie-going public, if only for the moment. And thus writers looking for a backstory for characters who are the children of

working-class

immigrants (Jewish and Irish, respectively) shift their origins from the Lower East Side to Brooklyn.