Besides sympathy, there is the issue of society becoming destabilized. Anything that leads to a significant number of unmarried males will cause huge social problems. This includes things that, for various reasons, we might otherwise want.<p>So there is a cost to polygamy, a cost to preferentially aborting female babies, a cost to women not needing men for survival, a cost to not sending men off to die in war, and so on. The result is a greater potential for violence and general mischief.<p>We tend to think of sex as low-priority compared to things like air and water and food. If we ignore the time scale though, and instead focus on what these things mean in an evolutionary sense, it is clear that they are equal. We need air... so that ultimately we can pass on our DNA. With a long-term perspective, it is clear that sex is on an equal footing with things like air and water and food.<p>When a good chunk of the population is being denied something so essential, we're facing serious trouble.