There are clear reasons why text messages and emails are so superior to voicemails. They give you control over the pace at which you consume the information.
Before visual voicemail you had no idea who called or how long the message was. You couldn't infer if it was a detailed message or a quick "call me back".
Even with visual voicemail, you know who called and the length of their message, but the topic or importance of the message is unknown.
With voice it's impossible to get to the point quickly. You can scrub through the message, but how do you know what info you're skipping over? You can't skim voice messages.
By comparison, reading a text message or email lets you know who sent it, when it was sent, how long it is, and lets you quickly assess the importance and topic of the message.
Voice has its place for sharing ideas, conversing, and general banter. But for sharing real information, it's a dead medium.