I think that the fact that marriage is not a business is exactly why I would suggect a prenup and separate finances. Obviously when you marry someone you don't expect them to change, and you don't expect your relationship to change either. Life happens, people change, relationships change. If there is no money involved in that situation then perhaps it relieves the stress on both. I have a close friend who's wife has recently been diagnosed with bi-polar disorder - he wanted to stick by her and help her through it. But her response was to refuse treatment and have an affair. 8 years ago he could have never predicted this illness or its affect on either of them. Now in her mental haze she is demanding hundreds of thousands in alimony - and spending hundreds of thousands trying to get her lawyer to get it for her.
Prenups just remove that element from the relationship so that people can focus on their thoughts and feelings and not on what each is worth, IMHO.
-------------------- He who controls others may be powerful, but he who has mastered himself is mightier still. ~ Lau Tzu