It's a really interesting concept because good communication and understanding between partners really does make or break a marriage. Simply the act of going through the exercise and discussing the terms of creating a prenup even if it weren't legally enforceable (which they usually actually are), might solve a lot of problems. Successful couples do this kind of stuff automatically and more or less instinctively. Dysfunctional couples fail not only at this but pretty much all other similar things.
But I'm not sure actually suggesting this as a policy would help much--people that are good at communication already discuss these kinds of things anyway, and those who don't bother are going to have lots of similar failings and miss lots of other "obvious" things like this. You can teach people these kinds of things, but only if they are open minded and eager to try. "You can lead a horse to water but can't make it drink"
If you're going to take the risk of getting married this type of stuff should absolutely be talked about beforehand so everyone's expectations is clear.