I don't know why you are being downvoted, as I find your reasoning valid.
My SO was never keen on the idea of having children. I thought I wanted to have children 5 years ago, but it was really just a default society behavior, not something I had stopped to think.
When I had no more excuses to delay having kids (healthy, married, stable job, two real estate properties) I really gave it a thought and concluded I didn't want to. I seriously touched the topic with my SO and told her I'd understand if she would leave me, but she said she was relieved by my decision because she also didn't want to have children.
What you said was one of the reasons "in favor" of having children, because you are right, life with children gets complicated in many senses but also gets simpler at least in life purpose. You don't need to "kill" time anymore for decades. But I concluded at least for me, it was not a strong enough reason to have children.