There are plenty of characters that don't have secret identities, with the Fantastic Four being the most notable examples in the comics, since not only are they the foundation of the modern Marvel universe, but also they never had secret identities. Then of course there are cases like Iron Man that casuals know about (even if they don't know that he did have a secret identity for like 40 years). But it depends on the characters and their personalities and what stories you want to tell with them. Remember right before Rebirth when Superman revealed his secret identity? It sucked. It did away with elements that were central to the character, particularly his regular life that keeps him as a down to earth guy. The Fantastic Four are celebrities in their regular lives, and Iron Man was a celebrity before he was a superhero. Making Superman a full time celebrity would destroy a significant aspect of the character. Having everyone know Superman is Clark Kent but not hassle him all the time wouldn't be believable. And there are characters like that, but frankly, they're usually secondary characters, and I think if they were focused on harder, people wouldn't buy it. There are also problems with characters that go through crazy shit that should affect their regular lives, but then they go back to having a secret identity. Like in the Death of Superman story, they mention near the end that Superman was actually only dead for like two weeks, in-universe. So when Clark Kent shows back up, it's kind of believable. Hal Jordan was either Parallax or dead for ten years IRL, which must be a significant amount of time in-universe. How the fuck does he go back to having a secret identity? Or does he not have a secret identity anymore? Shouldn't all the regular people be scared of him for what he did as Parallax? I've read pretty much every Green Lantern story (including Green Lantern Corps and that Ion miniseries) from Rebirth to Blackest Night, and I don't think I've seen this addressed, when it really should have been the first thing to address as soon as Hal came back to life.
This goes double for Barry Allen. He was dead for years in-universe. How did he just get his life back, including his secret identity? Iris West was dead for even longer. Enough time for Barry to get over her and get married again and then die and for his sidekick to grow up and have kids of his own. And when she came back, she did use a secret identity because the world thought Iris West was dead. But then eventually she became Iris West again. And then when Flashpoint happened Iris forgot that she knew Barry's identity, and presumably forgot that she was married to him and that they were both "dead" for decades. Okay, fine, I can accept that. But there was a period before Flashpoint when this made no sense. And then they remembered most of this stuff after Rebirth, so presumably everyone else remembered too, and then it didn't make sense again. It would be easier to just say the entire world knows Barry Allen is The Flash and Iris West is a time traveler from the 30th century. But that would destroy a significant aspect of the character. Also there was the time Wally West revealed he was The Flash, and that didn't work out long term. And he was a pretty different character from Barry anyway, since he was a superhero since he was a kid, and didn't have much of a life before he became one.
And with all the de-aging and disappearing for decades that has happened to the Justice Society, none of them could have secret identities anymore, right? But then why aren't people coming to their door and hassling them all the time? I guess they have all sorts of things set up to protect them from supervillains and stuff, but using things like that to keep regular people away from them doesn't seem very heroic. Why isn't the paparazzi harassing Alan Scott about how it feels to be a 100 year old man who looks at his children and feels compelled to tell them that he loves putting penises in his butt? Surely that would be quite a story. He should never be able to have a moment's peace. Even if he wasn't the world's first superhero.
>Only reason writers didn't do it is few early heroes had family to reveal it to (Superman's parents live far away from where he lives)
Superman's parents were dead on Earth-Two and Earth-One. Man of Steel is the one that kept them alive until the present day, in 1986. Also, originally they said the people who found him just gave him to an orphanage. I don't get how nobody at the orphanage didn't know who Superman was. Maybe they did and just kept their mouths shut. When they introduced the concept of Superboy in 1945, they said that the people who left him at the orphanage regretted it and returned to pick him up shortly after. The Kents then knew his secret identity in all the Superboy stories, but they died before he was an adult.
>The audience knows that status quo changes regarding it don't end up sticking and that they do not tend to lead to shake ups in anything else.
There are cases where it does happen, like Iron Man, Captain America, Flash, etc. Sometimes things get changed back after an extended period of time, but still.