It might be necessary to keep those scenes to tell us something about Carol’s character or about the Plurbs themselves (they might have thought about shortening the message but didn’t, and Carol might have asked them to shorten it but didn’t either). Or they included the voicemail scenes simply to mischievously annoy the viewer.

Honestly, I’m fine with either. I was annoyed the second and third time she listened to the voicemail, but now I kinda like it. It’s funny that they keep including these scenes.