There's so much stigma around this sort of thing. It's getting better, but the mindset that children are a gift and parents should be constantly grateful for that gift is still very prevalent.
The reality is that whilst children are absolutely incredible, life affirming and all that good stuff...an awful lot of being a parent is frankly, horrible.
In the history of the world, probably only baby boomers and maybe some of X thought this. Any time else in history, kids are there only due to the desire to fuck. Hell, the Romans drove a plant extinct with their need for birth control.