People are upset because it is a live action remake of the animated film from the 80s, wherein the main character is a white, red-haired, blue-eyed mermaid. Not the Hans Christen Anderson story. This exists to merely to pander to the liberal agenda.
I honestly don't care at all about the movie itself, as, if I even wanted to, I could always watch the animated version. What I care about is over-representing 10% of the American population in media. If you ever seen any advertisements these days, you would think you lived in South Africa. And this isn't just limited to America, it's very prevalent in Europe, such as England.