Of course, we’ll never have a utopia on earth and we’ll always find sins to commit…
But, I can see how an increase in chastity would help in many ways. As you said, there would be less STDs. We wouldn’t have adultery and the resulting broken marriages and broken homes and all the negative consequences that go along with it. Contraception wouldn’t be a mainstay, and the number of abortions would also greatly decline.
Obviously we cannot wave a magic wand and make things change. But I think it is very important to spread the message with regards to the Church’s teaching on chastity and the human person.
I know in college I came across many who were dismissive of the “conservative’s” concern with sexual issues. I even had a teacher roll her eyes and sarcastically say that all the world’s problems were caused by teens smoking pot and getting pregnant as her way of minimizing those issues in light of issues such as political corruption and so forth. I can understand that perspective, but I really think that the sexual issues are critically important. If you get sex wrong, you get the family wrong. And if you get family wrong, everything else falls apart.