Don't remember if its been suggested before, don't' really care either tbh.
Let people see when a message was sent in the chatbox, specifically for the big chatbox otherwise it would clutter the smaller one.
Staff have access to this information, no idea why it's not available for other users.
1. Easier to keep track of your own advertisement times.
2. Can see when someone sent a "hey I'm offering this/this" during dead hours. I.e. You don't want to be responding to someone's message at 2:18 am when it's 3:40 am just because the chatbox is dead.
I have no idea on how coding works or the way this site is coded but I would like to assume that making this a feature for all users wouldn't be too difficult.
I rest my case.
Gbye