I think the main reason that men refuse to pull the trigger is a realization that the deck is completely stacked against them. Most have friends who married young and got burned with years of spousal and child support.
I agree that what you are saying is true in a lot of situations but remember it takes two to tango and I do know of one situation where a woman I know dated a guy for ten years and guess what no ring. So what does that tell you?
That he is a lucky guy. Of course, depending on the state he could still be nailed with a palimony suit.