In the majority of movies and television shows now, lead characters are straight, white, cis males. This lack of diversity leads to a huge uproar in public opinion whenever there is any kind of diversity among those leads. These discussions occurred when there were women leads in Ghostbusters recently; similar events happened when directors decided to put both a female lead and a homosexual character in Star Trek: Discovery.
Although women and gay people are very common in the world around us today, popular opinion treats it like a big deal when they are put onscreen in mainstream media. The scorn of both critics and the normal people watching creates a cycle where the writers and other important editors decide to not include these kinds of characters to movies and television shows due to lack of support or fear of a drop in profit. Even though diverse TV shows and movies would reflect both individuals and society itself, minorities are underrepresented throughout them. People of color, and varying sexualities genders receive minimal representation, even though they appeal to middle America, media's biggest crowd to please.
The thought that all watchers just want straight, cisgendered people is incredibly wrong and another act of discrimination.The nominees for the 2016 Oscars were noticeably almost all white, to the point that the hashtag #OscarsSoWhite began trending. The lack of representation in films is such an ongoing issue with the public that the Oscars decided to make a five year plan to integrate people of color and women.
These ongoing discriminatory situations will contribute negatively to the mindsets of the younger generation that is growing up now. If people see discrimination as children, that mindset will always be stuck in their head and they will likely replicate what they observed. Not increasing diversity acts to continue the cycle that has been slowing for decades.