There is no such thing as "no-strings" sex. Sex always creates deep and reverberating consequences of which one can be cognoscente and contemplative of or not. To not care about the impact of your profound actions on yourself, your mate and your potential offspring is irrational and devoid of natural affection.
Good answer, and I think you’re right that casual sex often has unanticipated consequences, especially for young women.
But, like it or not, modern contraception has materially altered the presumptions and expectations of a sexual relationship. We easily accept that the invention of the transistor and the internet have changed the way people communicate. Why so difficult to accept that the invention of the pill has changed the way people have sex?