Comic book fans love their favorite characters. When comic books are adapted into movies, fans want to see those characters translated faithfully, as closely as possible to the source material. Apparently they are upset that the IMAGINARY character of the human torch is being played by a black actor.  In their minds he should be played by a white actor because in the comic book he is white.  Michael B. Jordan had the perfect response

“Eh, they’re still going to see it anyway.”

Here are some of the tweets:

It's 2014, if black people were only to play black make believe super heroes there would be no black super heroes in films. During the time, most of these comics were written most of the country was segregated. I'm sure Michael B. Jordan had to go through a lot to get this role at least give him a chance. This is a made up movie based off of a made up comic book. People really love to stay in the past. Have people have forgotten the Human Torch is not real ? When did it become that serious ?