Thing is, having kids brings perspective. You get to learn a lot about how you relate to other people, how far you can be pushed before you break, and how you deal with all kinds of difficult situations. While it isn't fun to figure out how sleep deprivation smashes your brain, it feels good to have come out the other side and sorted yourself out a bit better than before.
I want to say that we need to find a way for parents to walk the line between childless hedonism and raising small people. Some technique that removes some of the challenge and drudgery, perhaps giving more people the ability to learn and grow from child rearing without having to invest quite so heavily in doing so. The trick is that we have such a thing - it is called birth control. People these days don't have to have six kids like in times gone past. We can choose to have just one, and we can even have a lot of input into when we want that one to be.
But it isn't about parenting like people used to 100 years ago. We compete with one another, and it seems that parents are more than happy to hurl more and more resources at each child in an attempt to outdo one another. We *could* just let the kids do their own thing until they became old enough to be useful, but instead we dedicated hundreds of thousands of dollars and all of our energy to trying to shape the destiny of the few children we do produce. We have the option to take it easier, to find that elusive spot between duty and frivolity, but instead we simply pour all of our resources into a smaller number of vessels. You can't just opt out either, not without significant social consequences. What would have been normal parenting a century ago is criminal neglect now, and that ignores the strictly social penalties that would be expected.
I remember reading a quote from a mother who had some enormous number of children, more than ten surely, and she said that when she had two children they took all of her energy, and when she had a dozen, they still took all of her energy. I think that is very much true - our budgets for parenting in terms of money and time expand to fill any possible gap rather than being constructed based on what the children actually need.