I've asked this question also before, the conclusion that i came up with is that: When Women wear the ring they feel a sense of power (i got a man), security, and us as women love to flaunt that OUR MAN/ soon to be or Husband choose Me.
as for men, they dnt wear the ring because its a constant reminder that they have an obligation to someone else. That they are either taking a vow or made one to be everything that they may or may not be or be able to live up to. Men love to hv women chase them, (even if they r really doing the chasing) lol! But truly with or without the rings men have a choice,some wear them some dnt...... (w/out a ring gv's them an easier choice-@ the moment) :-)