There was a somewhat similar conversation about why couples choose to have children that you can read on EmpowHer: Advice from women with children?.
I have a 2 year old son, and shared some of your similar feelings and thoughts that you describe before I had a child. I was not a "kid person", and typically did not like other people's kids. I did not have the biological "urge" either, but someday I thought (down the road) I wanted a family, mainly because I had a great childhood, a sister I adore, and wanted that family atmosphere with my husband.
It's difficult to describe "life with kids", as we have friends who chose not to have children, and they are happy, content and have more money and time to travel and do more things than if they did not have children. I would like to say: I have enjoyed traveling more with my son; it is amazing to "see" things through his eyes--I notice so much more about the world around me that I "skip over". Everything is new to him, and he is introducing me to it. It's wonderful!
You asked, "what do they [kids] give back?". When it is your child (and you want that child), the love they "give back" is indescribable. I have always had love and laughter in my life, but I have never laughed on a daily basis until I had my son. He is hilarious! I also love my husband now even more; he is the father of my child and the bond we have raising our child together is insurmountable. It is difficult to describe "love", but you just don't know the love of a child until it is your own.
My life with a child is also richer, more meaningful, than it was before. I have perspective that I didn't previously; the world is not all about me. I am more mature, and I "get it" now. I have more friends than I ever did before (and I had plenty!). I get outside more---go to parks and museums and community events that did not interest me previously. I have a better understanding of my parents, and love seeing them as grandparents. Holidays are a blast!
I also think I would be a better supervisor than I was before; I've got some more tricks up my sleeve! :-)
I agree that there are some very poorly behaved children; some have bad days in the store that you witness, while others have poor behavior that is not controlled. There are many well-behaved children, who are not spoiled, not "alpha", are polite, sweet, intelligent and goofy! :-) Those children aren't as noticeable, but they "blend in" and do not attract our attention.
Sounds like you have a great future ahead of you with traveling, passion and joy! Enjoy it!