I dislike the idea because to me that'd limit what kind of characters I can play. I'd be restricted by my voice(which I hate, actually). Also, it'd shatter what I imagine other characters sounding like, it's somewhat a movie vs book thing. Why is the book nearly always better? Your imagination essentially makes it perfect, a voice would shatter the voice I had unconsciously given them. Also, top it off with needing to record and not everyone has the equipment or time(essentially alone time). I wouldn't want anyone hearing me talking like some of my characters do, you can write anywhere, recording voices not so much. 

Overall I dislike it. I'm sure someone could be able to pull it off though I've heard many tabletop and skype rps work this way, so perhaps you should look into doing a skype call group.

Tl;dr: In short, I'm a writer not a voice actor.