To be human is to hold contradicting understandings of reality in equal measure. The amount of people who hate the idea of animal cruelty (or environmental destruction for that matter), yet still consume animal products is astronomical.

The environment will never be saved by trying to convince people to not have kids. It's a biological staple of existence stretching back billions of years, and we as a species will never give that up.

Having children gives us a species a more personal stake in the planet's future, and it would be better to focus our energies on that angle instead of demonizing people who agree with you 95% of the time.