I'll prolly regret jumping into this but it seems to me we legislate age issues such as this based on the idea of over-engineering based on safety. Perhaps (and I don't believe this) but perhaps .1% of 14 year olds could understand the ramifications of sex with a 30 year old man (consequences of having a baby, sexually xmitted diseases, etc.) and then safely take on the relationship.
But who is going to "test" all of them to make sure they understand? It ain't gonna happen. Therefore we up the age to what it is now so as to cover most people, assuming they know WTF they are doing (even then many don't).
It's like the age recommendations on children's toys (without legal ramifications). Yea you could buy the toy below for a 2 year old and some could safely use it, but most would choke on the parts, and the gubment knows people are sometimes too stupid to do the right thing for an innocent child, therefore the age recommendation of 3+ years. That's why children have a safety "label" for an age on consent that safely covers the vast majority, even though some could be of a lower age.