The problem is, "tradition" is a very weak crutch. It's "tradition" that Blacks are inferior to whites, that they are 3/5ths of a man. Should we keep that particular tradition? It's tradition that a woman's place is in the home, she is the property of the husband. Hell, it wasn't until the 20th Century that women were allowed to vote. How's that for tradition? (Honestly, every time I hear Palin, Bachmann, etc go on about "bringing back Traditional American Values", I think, "Then what are you doing speaking into a microphone? Get your ass back in the kitchen because that's what you're asking for.")
The "tradition" of marriage is two people who wish to make a life-long commitment to each other.