I loved what was done with Defying Gravity. They controlled your focus and did not give in to audience desire to get to the beloved and cherished end "battle cry". They held it out for as long as they could. I dont think you give enough credit to John M. Chu. After Crazy Rich Asians (a musical without musical numbers) and Into the Heights (a full-blown musical). He's a master director who reflects his knowledge of the form with nods to Hitchcock, Demy, Bergman and Minnelli. There is a lot to digest in this movie while still pushing the plot firward. If you shaved off 20 minutes, you would be irritated and not know why. The audience needed to digest the brilliance of execution of the musical numbers as well as the emotional arc. As well as the social issue related material. The fact that a woman with African features is cast as Elphaba is something that for the past 20 years has been almost completely avoided, the way that we do in real life. And that fact and process has to be digested and integrated into our empathy generated by the fictional plot. I suspect you will watch this film over and over through the years and not think it's too long - for different reasons. (The Ten Commanments, Ben Hur, LOTR, the Judy Garland version of A Star is Born, etc.) There is the element of super-hero epic that will make rewatchings of this film easier for some people.