It's different when you've made it.
I never really minded kids, I was okay with them being near me on an airplane, and it kind of perturbed me that I had to stop waving back at them or responding to small talk from children because everyone is a pedophile and the parents will chew you out.
Despite that, I swore I would never have one. "I like being alone too much", "I don't want a huge responsibility cutting into my hobbies", "It's enough to watch my nieces/nephews and then hand them back". When it happened to me, there was a major shift in my outlook, overall thinking, and probably hormones or some shit. My wife did go through a lot of pain, yes, but it was a surreal kind of "okay" pain despite the intensity and duration. She got to feel a human being grow from a peanut into a real person, inside of her. I'm actually jealous of that, because despite how much attachment I have to my daughter I will never have that level of complete bonding that took place.
I'm still generally uncomfortable around other people's kids, but your own kid is awesome. You look into their eyes and they smile, and you see half of yourself and half of someone you love very dearly combined into one individual. I'm not saying it's easy, and for a lot of people it's an undertaking that they probably shouldn't consider until they absolutely know they want to. I don't even hear crying/screaming as an irritant anymore, I've adjusted to little powernaps to adjust for lost 8 hours, and if you have a loving partner you can work together so that each of you can have time to do the things alone that you enjoy doing.
I'm excited as hell to have her talk back, and to see how her personality develops. To watch her question, and develop her worldview with the help of my (probably fucked up) information. I know a lot of this is the same bullshit rhetoric you get from people who shove pictures of their kids in your face, but it's where I'm at in my life right now. I'm not sure there's a biological disposition to truly care for other people's kids that you see in public unless they're on fire or something, or you're someone who teaches/works with kids because it's your calling.
And honestly, I won't judge anyone who cannot ever fathom the idea of ever having kids. It's not for you, cool. It's a shitload of work and responsibility and sacrifice for the many intangible rewards it gives you. There's a whole lot of people on this planet, so if people hate kids, are asexual, or homosexual, thank you for (inadvertently) stemming the tide of overgrowth. I just figured I would let people know that there's a love deep inside of yourself that you can only feel by having a child, it's not all negatives, and a lot of the negatives either quit feeling like negatives or are remembered as being "not so bad".
1 Sidenote (because this needs to be longer), immediately after Tali was born, my wife said "Never fucking again. It's not happening. If I say that I want to do this again, call me a liar because there's no fucking way I'm doing that again". 3 months later and she's already talking about the timing of giving her a sibling, saying that it "wasn't really that bad". I hear there's a hormone that actually makes the whole process seem not as bad in hindsight. Such is life, and being an animal on a floating and spinning rock.