Not necessarily. The option could go either way - you might be the wealthier party but it could also be that your spouse is the wealthier one. You could also have a prenup, but that would still involve lawyers.

I just don't see the benefit to the standard government marriage scheme. Domestic partner benefits have basically the same upside and very little downside these days. From a legal perspective marriage is almost entirely about property/money. There are plenty of people who have a loving and marriage-like relationship without getting the state's permission (piece of paper).