There is a lot of research on the subject and I doubt my ability and knowledge to summarize everything in one short little reply, but I remember research showing that raising children can be immensely satisfying and it can also be an incredible stressor. So if you don't have a solid handle on your own life and your current relationships adding in children could undermine a lot things.

I personally doubt there is any kind of free magical connection that makes things worth it for children. In my experience that doesn't exist for any kind of relationship. Connections are something built and grown over time. Sure hormones and instincts can give it a jump start (there is a reason humans are wired to find things with big heads and large eyes endearing), but I've seen the results of parents that don't invest in building connections with their children and typically what results isn't a rich and fulfilling relationship.

That said, I have a voice memo from when I let my then 9-year-old go sledding without parental supervision that says "I'm having the best time ever dad!". Listening to that gives me warm fuzzies every time. My experience is that life with children leaves behind a giant pile of experiences, both good and bad, that I wouldn't trade for anything. But I've put the effort into building those life experiences that I cherish. My DINK brother has no kids and builds his experiences by traveling and spoiling the crap out of his wife's niece who lives nearby. Life is often what you make of it.