Fans will remember Philippa Georgiou from the initial episodes of Star Trek Discovery, as she was mentor to Michael Burnham. Burnham in a desperate gambit to stop the Klingon’s would eventually lead a coup against her and though they patch things up it still does not stop Captain Georgiou from being killed on-board the Sarcophagus. She was a wise leader and successful in taking Burnham under her wing, even developing a Mother/Daughter like relationship between them. As a captain she was brilliant, she did not always do what was expected and tried to work around rules.
“All warfare is based on deception. When you’re able to attack, you must seem unable.”
– Georgiou, quoting Sun Tzu to Saru (DIS: “Battle at the Binary Stars”)
So why does it make sense for her to return as the Emperor? Simply put thematically this makes sense. With Burnham off to places unknown and still suffering from getting her captain killed, possible this may be a way for her coming to grips with what happened. On top of all that and not come off as a little racist Hoshi Sato was the previous Empress, perhaps Georgiuo is her Non Japanese but still Asian descendant. More importantly thematically it would mean a lot more to the plot. Finally it would be nice if the Emperor was female and still used the title of Emperor.