If both party's motives are pure, they should have no problem with one.
Well, if someone asks for a pre-nup he or she is already considering divorce to be a event with a rather high likelyhood. Is it really smart to marry someone who considers divorce a likely event?
It means nothing of the sort. It means they understand that life isn't a fairy tale, that anything is possible in human relations and that includes divorce, like it or not. Is it really smart to marry someone who lives in a fantasy land where bad things like divorce don't happen? Or worse, just don't happen to them because they're somehow special? Likelihood isn't the issue. Possibility is. Its always possible.