* How much time do people really save, the call in the example is less than a minute. Maybe if you need to call like 10 places it becomes more helpful, but as companies get a bigger online presence (and they are) this technology becomes less useful. You can already make reservations/book appointments, find contracts pretty easily online.
* You can't be 100% sure that the AI won't make a mistake or sound like a total jerk on your behalf. Ok sure, the tech will improve but it will be a long time before humans will fully trust AI to represent you.
* If people find out you're calling them via some automated bot they're going to think you're a tool. Everyone remember Google Glass?
* What the hell is wrong with human interaction anyway?
edit: formatting