Why is population reduction such a taboo subject?

We're coming up on 7 billion people on the planet. Wouldn't life be better for everyone living on Earth if there were fewer people (more space, less competition for land, jobs and resources...etc.)? I know some folk's brains jump immediatly to Hitler or communist China when the subject is brought up, but what if there were a completely humane way to lower the global, human reproduction rate (say with education, stabilization of governments, and dare I say it, universal health care)? What would be wrong with that, other than it would require an unprecidented level of global cooperation and organization?