One of the current trends in media is the paired notions of world-building and transmedia. You don't just tell a story; you tell a story in the scope of a broader world that can then be expanded upon in multiple outlets. Star Wars is a classic example. There's a Star Wars universe that was initially developed over the course of three movies. But George Lucas had other notions going on in his head that didn't make it to the screen. As did other people who worked on those movies. As did people who just saw them. Those ideas got expanded upon in other outlets like comic books, novels and bad made-for-TV holiday specials. Though most of the infamous 1978 Star Wars holiday special comes across as a cheap attempt to rake in some extra bucks on what may have been just a fad, it is notable for debuting Boba Fett two years prior to his "introduction" in Empire Strikes Back. Which suggests that Lucas was thinking about expanding the Star Wars concept beyond the movies pretty early on.
In any event, world-building and transmedia are considered the "now" approach to story-telling. If you're making a movie, you need to make sure the accompanying video game ties in with it as seamlessly as possible. If you're making a TV show, you need to make an accompanying comic book. An so on. Like anything else, it can be executed well or poorly. There's nothing wrong with the concept per se and, although it can be viewed cynically, whether or not it works largely depends on how good you are at actually telling all these stories in these different formats.
I recently came across a comic book series from mid-2010. It's a science fiction story, a little vague on the central concept but well-drawn with good dialogue. I wouldn't go so far as to say it's well written, though. See, it has this problem of providing too much world-building. The story starts in 1947 Roswell, and goes on at length (fully 1/3 of the first two -- and, to date, only -- issues) explaining how aliens came down and, wanting to the help the human race, did some time travel business to change the course of human history. Which is nice and all, but the main story occurs in this new, alternate timeline where there's spaceships and lasers and all sorts of fun, science fiction-y stuff. That has nothing to do with the backstory. They could easily have dropped the backstory parts and there would have been absolutely zero loss in comprehending the main story.
Go watch Star Wars: A New Hope. If you didn't see it when it first came out, try to forget everything you know about that universe. The movie starts with Darth Vader pursuing Princess Leia, and you pick up in the first few minutes the basic stolen-plans-for-the-Death-Star plot. Does it go into a long, in-depth discussion about how the Emperor tracked down and killed all the Jedi? How that was preceded by the Clone Wars and what that was all about? No. We get a couple of off-hand lines of dialogue about a quarter of the way into the movie. Twenty seconds out of a two hour movie.
And that's part of what people liked about the original movie back in the day. "Clone Wars? What the hell are those?" It wasn't germane to the story but it let the audience know there was a world out there beyond what we were seeing on the screen. Lucas' world-building was somewhat unintentional (he had simply written a story far too long to capture in a two-hour movie) but that still informed his story-telling in A New Hope. The audience picked up on and responded to that.
But if you spend your time trying to tell all your backstory along side your lead, you're going to lose your audience from a lack of focus. "Why am I learning about this guy, who's dead and buried by the time the protagonist is born?" The story is about Han and Luke, not Qui-Gon and Padme. It's about Frodo and Samwise, not Beren and Lúthien. It's about Superman and Batman, not Jor-El and Thomas Wayne.
As a creator, it does help to put some serious thought and consideration into how your worlds work. But it doesn't necessarily all need to be spelled out for your audience. Certainly not at the same time you're trying to tell your central story.