One of the few measures I'd take, if I were god, would be to replace STDs with...STAs (Sexually Transmitted Abilities). Instead of annoying infections, the only thing you'd get from your sexual partners (mental disorders aside) would be a portion of their skills.

Consider this: we'd all have free access to knowledge, we would all get something in return; a most useful souvenir for even the least worthwhile of occasions. A one-night stand with a spanish teacher, and you'd manage the basics in spanish. After dating a pianist for a few months, you'd be able to play the piano quite well. A long relationship with a physicist would turn you into a quantum physics expert. You might want to avoid fucking a proctologist, though.

Now, you may ask, why make it so hard? Why not transmit information via a a kiss, or a safe and simple handshake? Well, that would be far too easy. The point was to get you to invest a part of you, however small, into the exchange; to attempt establishing a connection, no matter how insubstantial. Wouldn't that make procreation so much more promising?(remember, no STDs either)

Well, as for the con's...Overpopulation for one, not to mention the danger of having too much knowledge in the wrong hands. Imagine an even more crowded world filled by over-confident individuals, possessing bits and pieces of all-too-effortlessly acquired wisdom.
Perhaps, nature did the right thing, after all.