It goes along with a generally increasing infantilization of society. Many of the most noteworthy storytellers of yesteryear had seen much more of life and the human condition by the time they started writing than the average modern Westerner will ever see. Tolkien served in World War I, including the Battle of the Somme. Rod Serling earned a Purple Heart as a paratrooper in the Pacific Theater of World War II. Many of them worked other jobs before turning to writing later in life. Thomas Hardy was originally an architect. Arthur Conan Doyle was a doctor. Dickens was a bootmaker and a journalist. Many of them lost infant children to disease or lost parents at a young age. Lovecraft's parents were thrown into asylums and died when he was relatively young.
Many if not most if not all of today's writers are among the most privileged, sheltered people in human history. Few of them have lived a life that would be worth telling others about. Most of their problems could be solved by logging off of Twitter and eating less. They spend 18 years in schools that coddle them and refuse to challenge them, graduate with a degree related to writing, and start bitching about student debt on social media until some soulless corporation hires them to punch up a script written by a computer algorithm. Their greatest struggles are fighting for rights they already have in a society that's already giving them everything they want on a silver platter. Even if their stories suck shit, massive corporations and thousands of vocal idiots will run cover for them on social media, so they're completely insulated from the consequences of their greatest failures. Sometimes they'll even fail upward. They spend more time absorbing fiction than living a real life. They're not able to draw on meaningful life experiences to write interesting stories, so they have to draw on what they know -- young people fucking each other in the ass.
Society's ass was also generally tighter once upon a time, for better or worse, and so were censorship standards. You couldn't show teenage lesbians making out on screen until relatively recently. At most, you could allude to it with some vague innuendo. The Great Awokening has made it not only permissible to do gay shipping shit in plain view of the public, it's made it a moral good in certain extremely vocal and consumerist circles. It generates buzz on social media no matter what happens. If a show teases two gay characters, some people will complain about it because they hate gay shit. The writers and their corporate overlords push back against "bigotry and hate," which generates buzz. Some people will complain because they're just bored of gay shit, or just want a decent story, or whatever. The writers and their corporate overlords will accuse them of "bigotry and hate" anyway, which still generates buzz. If nobody complains, someone will invent a fictional narrative about "bigotry and hate" anyway. Buzz supposedly translates to revenue, which is more important to writers and their corporate overlords than just telling a decent fucking story, so they encourage it.