we all would like people to share their code with us, but forcing them to because of your license is extremely anti-freedom to me.

address this culturally, that is the only way to address this completely. legal means cannot fundamentally redirect the culture of a society and make them believe that sharing is better for everyone. if you want a society that shares what it creates, then help create THAT. forcing people to do it pushes them in the opposite direction, they want to grasp their things even tighter than before.