I think it's a bit harsh to presume that just because someone fully grasps the gravity of what mothering entails that this means they are too selfish to be a parent. Plenty of other folks just launch right into it and only find out when it's too late that it has completely taken over their life.

Calling childrearing a burden is calling a spade a spade. The key point is that the burden should be worth it to the people who are carrying it. Also, it should be shared between both parents in a way that is acceptable to both parties.

One of my sisters is a SAHM with 6 chilluns and a husband who travels a lot and brings home lots of bacon. She is quite content with shouldering 95% of the childrearing load. For my personality, I know that being in a situation like hers would cause me to feel resentful and depressed. I'd probably gnaw my own arm off to escape a situation like hers!

Until I get to a stage in life with a partner that is willing to divvy up this burden in a way that works well for both of us, I won't consider intentionally conceiving and bearing children.