Video chat often has better audio quality than phone calls. HD calls are still rare, even on VoIP. POTS is almost guaranteed to cut off at 3.2kHz which cuts out a lot of information.
> Video chat often has better audio quality than phone calls.
That has not been my experience. Generally the audio suffers as the compression algorithm switches to accommodate poor network performance.
This all might be moot if you're on the same LAN, such as in the same office (that is, until you have dozens or hundreds of video chats eating up the bandwidth). But add in folks in another location and/or working remotely, and video chat is just terrible.
It's not that bad normally (I get to do that every day). ADSL 12mbit was enough to handle high quality Google hangouts up and down. More people only impact the centralised service, not your connection (unless you're using a really terrible conference implementation)