Let's say we could adjust populations to be 20% male, 80% female, little by little

Violent crime would sharply decline. Suicide would sharply decline. Women wouldn't be living in constant fear. Sexual abuse of women and children be greatly reduced. Women wouldn't face so much gender discrimination in the workplace. Homelessness would be greatly reduced. Human trafficking would be greatly reduced. The illicit drug industry would probably collapse. Politics would be led by women, so all political problems men cause would end. Men are the ones who start wars, so that would end.

Women supposedly don't need men, so most of them not pairing up would be fine.

Sperm is cheap, so the population would probably be fine. Many women might prefer raising their own children by "the village" anyway.

Women can be trained in male dominated jobs that keep society running, so that wouldn't be a problem.

Are there even any drawbacks? Why are we not pushing for this? It wouln't be a perfect utopia but preferable to the status quo?