Fairweather put it better than I did, T_G. I realize that everybody's got their own, valid views on this subject. And I seriously doubt whether any of us will be influenced by others on it!
I used to say I skipped my first marriage, 'cause I waited until 30 to get married. Just didn't meet "the right one" until then, and enjoyed years of being a bit of a swordsman. Reasons I would not want to go back to being single:
-I'd miss 'er!!
-dry spells suck , no matter how good the other times are
-I enjoy women, period, and would eventually want to spend most of my time with somebody I liked. I've never met anyone that I've liked as much as her
-sure, we've both changed in 15 years, but we share a core interest in several basic things
That being said, everything could turn to shit tomorrow, as people here have noted happens a lot. Therefore it is worth a little bit of constant investment in doing the things that you know will keep your spouse satisfied/comfortable with you and what you do.