Not everything you say has to be heard or understood. Sometimes a little mystery is welcomed. There are some things that need to be hidden in the message; communicated, but the severity of the message underplayed. Sometimes, the understated voice is someone’s saving grace.
By using the understated voice, the character seeks to downplay the importance of the message they are passing to their audience. A very serious message or an event that had very awful consequences is described in a way that makes it seem like a normal occurrence.
Podcasts, motivational blogs, and documentaries about contentious issues and traumatic events will often use this voice. Politicians also use it to downplay their opponents’ achievements, or their own shortfalls. It is an effective way to deliver bad news, especially on matters that the recipients do not care so much about.
The calm demeanor in which the understated voice is portrayed hides the actual significance of the message being passed. The message is trivialized by how it is communicated, either to soften the blow to the affected party or to outrightly trick them on the severity of the event.
Dark humor comedians sometimes use the understated voice to water down whatever they are to say, luring the audience to a false sense of relaxation before they can really think about the joke. An intentionally polarizing joke can be framed to sound normal, until you comprehend it in full and see its darker side.