It would be convenient for the user, but not so much of a viable option for exchanges that are looking to operate a cost efficient suppert desk.

I know from experience that most of the users who seek support through live chat are doing that for the most silly (non support related) reasons, which is something you can't protect yourself against. Another thing is that when for whatever reason the live session ends, you will need a ton of luck to connect back to the same person you were chatting with.

More manpower behind email support would be appreciated. If they can operate so that you get a reply within a few hours, that would be ideal.

The main thing is that people expect too much from exchanges that are clearly profit oriented. They will never be perfect, not even remotely close.