I tried to write some words about this playlist but it kept turning into some sort of thesis on what happens to theater kids when they grow up, and really who needs that. In brief: some of them go to art school and start bands rather than perform in musicals, so there is this theatrical strain you can find in some artists playing otherwise straightforward genres. The most recent hugely successful artist I can think of like this is Florence and the Machine
Frankenixon! Holy shit.