@OmSigDAVID,
The thinking is that at least the bulk of an entire generation of criminals was basically aborted.
I view that as largely correct as far as it goes. Amongst the things which Freakonomics does not mention is the 12M - 25M Mexicans now illegally in this country to take up the slack for that missing generation...
Of course, the lottery system which was in effect in 1955 in which a certain number of teenage girls produced babies for adoption is not going to come back. The real solution is that we have to again make it both respectable and economically feasible for young Americans to marry and start families in their late teens. What we've been doing for the last fifty years or so clearly is not working.