You're looking at what, 2-5 years of that? Per kid? Plus the huge time commitments for all of the other burdensome stuff that having kids entails, like school and transport and non-school education? 2-5 years out of a lifetime isn't much, but 2-5 years out of your 30s or early 40s is a gigantic percentage of your remaining not-old life. Unless you're a major biological outlier, you're not traveling on sporting vacations or backpacking trips or hallucinogen-fueled music festivals when you're 55. You don't get a lot of useful years remaining as a not-old person by the time you're old enough to responsibly have kids. It's a gigantic tradeoff and to minimize it like this is woefully shortsighted.
It's fine if you like kids and didn't have actual plans to have fun in your 30s or 40s, but people with exciting lives will lose a lot if they suddenly have to dedicate almost all of their free time for 5 years to their offspring.
This is also assuming that you have more than enough money to spend on kids and all of the other things you like to do in life. Even if kids took 0 time (which as we know they do not), this is not true for most people.
> You actually like hanging out with your own kids.
Some people do. Sometimes children grow up to be terrible, for reasons outside of direct parental control. Not every potential bad final outcome can be avoided with good parenting. Not everyone who thinks kids might be a good idea is capable of being a good parent.
I personally find the idea of having huge, tremendously expensive, hugely time-consuming, unavoidable responsibilities like this in the middle of the prime of my life to be a living nightmare, for well-considered reasons which you seem to simply handwave away as trivial. Having kids and raising them well must necessarily become one of your primary goals in life, displacing others as there are only 24 hours in each day.
We don't have a lot of time left.