I don't know if you've heard of this yet but Warner Bros. and Zack Snyder had quite a tumultuous working relationship and the problems between them are well-documented. Some folks assume that the cracks in their collaboration began to show after Batman v Superman: Dawn of Justice received a generally negative reception. However, it seems like WB and Snyder already had issues while doing Man of Steel.
Turns out, Snyder wanted to use John Williams' iconic Superman score on Henry Cavill's first big-screen outing as Superman but WB decided that it wasn't the right fit for the new iteration of DC's flagship superhero.
According to Man of Steel storyboard artist Jay Oliva, the production company rejected the idea despite Snyder wanting to use the theme. In the end, Hans Zimmer was tapped to create the film's Superman score and while it isn't exactly on the same level as Williams' theme, it still sounded phenomenal, and admittedly, Oliva thought it was the smarter decision.
He wrote: "If I had heard that then I would have responded that both Zack and I loved that theme but the studio wouldn't let us use it because they wanted something new for this Superman. It turned out to be a good thing because Hanz' theme was perfect."
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Personally, while I love Williams' original Superman score, I feel like it wouldn't have worked with Snyder's take on the character who was obviously grittier and didn't share any similarities with Christopher Reeves' version. And it's probably the reason why when Joss Whedon incorporated the theme in the theatrical version of Justice League as a homage, it didn't quite click.
Man of Steel is available to stream on HBO Max.