The thing is that many of the advantages of a phone call (and in-person talking) over email etc are due to the very low-latency and the ability to quickly react

The thing is that many of the advantages of a phone call (and in-person talking) over email etc are due to the very low-latency and the ability to quickly react to nuances and adjust what you're saying to reflect them. A voice message basically does not have any of that. Certainly it will have some advantages over text, but a voice message isn't a phone call.