I wouldn't worry too much about expiration dates...we once took 20 yo vests off of the floor of our basement and shot at them...they worked fine. If they were ever struck by a round? Different matter.

In terms of daily wear...I always wore one when in uniform and still have 2 in my car. One for regular use and a plate carrier in case I have to really "suit up". But they are not comfortable and unless you have a job that requires one I doubt that a "normal joe" will wear one daily for long.