Even though Connor dies at the beginning of the story, the character actually plays a central role in the musical, often acting as Evan's conscience in various scenes, including the performance of "Disappear." Since some of those Connor-centric songs have been cut from the movie soundtrack, Connor doesn't have too much screen time in the film.
Why it hurts the adaptation: Through various musical performances and bits of dialogue in the musical, you really develop an emotional connection to Connor as the storyline progresses. However, with Connor's big moments being cut from the movie, that emotional connection is severely lacking by the time the film ends. It's not until the very end of the film that we finally begin to learn more about Connor, and by that point, the credits are already rolling. Mike Faist was such a charismatic force as Connor in the original production, and I wanted to see the movie adaptation use Colton Ryan's talents in the same way.