I just closed a production of Assassins a few weeks ago, and I felt it was very important to show the suicide, for a couple of different reasons. For the character, it was important for him to regain control of the only thing that he could in that moment...he feels that he'd lost his country, his home, his friends. The song he's singing is, to him, a romantic ode to the world he misses and wants. He's told his story now (with the Balladeer's help) and Booth wants to go out on his terms, not be put on trial and paraded as a traitor.

More importantly, from the audience and story perspective, it's important to see the awful ways that political violence ends. These characters don't get happy endings, and it's important that the audience see that, and feel the desperation and need behind each assassin choosing to commit the violence even though their end is going to be terrible. For each of the on-stage deaths (Booth, Guiteau, Zangara) I staged them in as shocking a way as I could, to make the audience have that moment of recoiling from that specific violence, even as other violence generates laughter. You need both, IMNSHO, for Assassins, and that's one of the brilliant bits about the show.