I agree with this notion. However, in the eyes of the Roman Catholic church (and devout baptized christians for that matter), it is much more than a paper. It's a sacred oath to honor, protect and cherish one another! Just a bit more than the conventional "I Love yous"...
Same goes for Muslims and the Nikah in the Quran. Yeah, it's a "contracted" form of commitment, but its also a proclamation of faith considered a "blessing" and a source of stability.
In the end, its completely useless if you don't feel it, I concur. However for many, it's the ultimate religious undertaking.
Personally, I'm not sure I'll ever take this ultimate leap. Perhaps I'll see things differently in my 30s