there will be situations where you cant check is the address really have that bitcoins or not, so i expect ppl will make offline bitcoins checkers, if the date is on the coin ppl can easily accept or not the bill/coin
I'm trying to understand how having the item marked with the date helps to make it easier (safer ?) to accept.
Coin A gets used, thrown on ground.
3 months later, someone finds Coin A.
Someone attempts to pass off Coin A as legit.
Having a timestamp wouldn't fix anything, but it could cut-down on scenarios such as above.