But it's not about freedom or 'exercising' the right to have a lot of kids, it's about what the consequences are. Eg. Octomom. Raising good kids has nothing to do with it, it's about the carbon footprint humans put on our planet, and to me the ethics of it. I agree with what Gene said on how it's like trading 12 kids for 12 deaths (or however it said, sorry it's late). Humans should take accountability for the planet, or at least for the harm we have done to it.
 
If I took half an hour showers every day, other people in my house wouldn't get enough hot water.
Or, maybe if I drive a vehicle that has double the MPG of a typical car, I might be able to sponge the damage to the earth done by my neighbor that drives a 5 MPG luxury sports car.
Maybe I can help extend the life of this planet, habit by habit; act by act, and example after another. Isn't our planet a ticking time bomb?

I think having a ton of kids works the same way. Not all humans get a nice place to live. If I gave birth to 8 children now, EIGHT good children that I raised and that (I hope) will live in jolly good big townhouses, which unfortunately will deprive several hard-working and deserving immigrants, homeless, even my own descendants down the line won't have a place to live. Or, I could have made the easy choice to lessen my impact, and had two children, and saved space on this earth for 5 other families places to live in. I want my descendants to enjoy however much time as possible before this thing self-destructs. There is an expiration date on it right?

Like NightShade said, the way continents live right now, it'd take more than x planets to sustain, and etc. That's the point it makes...it's selfish. And it's foolish. We're running out of space. Food. Everything. Air. "The world could use one less man." What's the cost of a planet? 12 kids? But we can't trade lives for another planet, the universe doesn't care.

On a personal note...being 1st generation American-born-Chinese (ABC), most of my parents and uncles and aunts have one child because of China's one-child policy. See: http://www.telegraph.co.uk/news/worldnews/asia/china/9933468/336-million-abortions-under-Chinas-one-child-policy.html

As a child this logic drilled into my head when I was younger. My parents told me overpopulation was srs bsns. You can bet my native family's been affected by it. Like you, I thought it was "WRONG, it's very wrong...that's so horrible." Even though my parents weren't bound to these laws, I am an only child. But hey, it works. And the 'commie leaders might have shed tons of carbon footprint, maybe bought some more time for the planet. For me, it doesn't represent a right or wrong, whether I believe in abortion, whether I believe in god or not, but it makes the point that overpopulation is serious, and measures need to be taken. Overpopulation needs to be Lordship'd.