We have health insurance, car insurance, home insurance...all just in case things don't go as planned. The more you have to lose, the more insurance you should have. Romantic? Nope. But how much of your day to day existence is all about romance? Stuff happens.
No matter how well you know someone, there are always a few doubts. People experience life grow and change...sometimes in different directions. It's not romantic to think about such things, but then, there's not much about a divorce lawyer that's romantic either.
Pre-nups are not the stuff of romance, that's for sure. But being able to talk about everything in a relationship...even what to do if the relationship ends, seems more healthy.
The problem with your logic is that you're comparing divorce with an accident, and it never is accidental. Someone is always at fault.
I'm not married yet, so please don't confuse me with an expert, but marriage is a commitment that both parties must conciously adhere to, regardless of how they feel from time to time. When they say their vows, they say, "For better or for worse, for richer or poorer, in sickness and in health, until death do us part." They don't add on, "or if she burns the toast."
I will not ask for a prenup, and I expect the same from my future wife.