So basically what you want is an abstinence awareness campaign (not just before marriage, but a lifetime of celibacy, good luck with that), even though safe sex campaigns have been much more successful.

You are calling for people to be self-aware to realize that they shouldn't have kids (as if people having kids is a totally rational decision, when it usually isn't), ignore their raging hormones that cloud rationality, while you ignore the huge number of unplanned pregnancies that you will never come close to eliminating without focusing your efforts on access to effective birth control.

Your opinion is unpopular, because without force, you are simply recycling failed and marginally effective ways to keep people from doing the thing that our body does everything it can to get us to do: reproduce