According to Lucasfilm creative executive Pablo Hidalgo, there had been some talk about including Coruscant in Star Wars: Episode VII – The Force Awakens.
“Basically [J.J. Abrams’ production company Bad Robot] wanted it blown up; [Lucasfilm] didn’t”, says Hidalgo on Twitter. “Hosnian Prime was the unsatisfying middle ground. It happens.”
As a reminder, Hosnian Prime is the capital of the New Republic that gets destroyed by Starkiller Base in the movie.
“It’s not all that deep”, adds Hidalgo. “The concept art resembles Coruscant because for a time it was; but that planet had the potential to be featured in something else in development so it was changed to a different location. Not really all that newsworthy.”
Hidalgo also says that at an earlier point in the development, when Michael Arndt was writing the script with advice from George Lucas, “the bad guy in the depths (which became Palpatine on Exegol) was gonna be on Coruscant.”
Maybe the character mentioned here is Darth Maul, who was supposed to be the main villain in Lucas’ treatments for the Sequel Trilogy.
Ultimately, however, the main planet of the Prequel Trilogy never appeared in the sequels. And it barely appeared at all in the other post-Lucas films and series, which is a shame.