The idea that the Phantom is vain and deluded about his own ability is a fascinating one that I could definitely see being the focus of a story.

I’d also argue that the notion of a Phantom who loves and breathes Opera, but simply doesn’t have the voice is a potentially-excellent one (Albeit difficult to integrate into the stage musical version of things), since this would help fuel his obsession with the genuinely-gifted and his vicious hatred of those who ignore his expert advice (As well as other mediocrities) since that expertise is all he has.

It also occurs to me that a cinematic adaptation that leaned more into the Grand Guignol origins of the story might potentially allow a film to carve out it’s own distinct identity (Since in a film one can focus on little details in a way no stage musical can get away with).