My two kids were planned. So many reasons...

--To pass on a piece of me to the future
--To procreate--how profound, how biological....
--To create life with my husband, to merge our genes, to offer the world a manifestation of our love
--To have a loving relationship with my children. I had a c**p relationship with my mother and I have had a desire to be a mom in a different way and be to my kids what my mom was not to me. It has been very healing.
--To give of myself fully to another human being (I did not have that kind of relationship in my marriage)
--Lastly, I wasn't allowed by my husband to have the career I wanted in life--a lot of doors closed for me because of our relationship--and having two great kids helped console me and fill the gap. Maybe not a great reason, but at least it wasn't the only one.

Great outcomes for me of being a parent:
--I have become less selfish and self-centered, because the kids always come first
--I have gained some humility. I thought my mom was a bad parent, the proof being how unhappy I was and how screwed up I turned out. But when I had my own two girls, I realized how important biology is too, and there are things about them I could not alter no matter what environment I provided. This has made me have more empathy for my mother.
--I have become more loving and giving. Something has opened up inside.

FWIW, I never had a maternal instinct until I was pregnant. I never liked babysitting, holding infants, and in fact, felt awkward around small children, like they were a different species. All that changed when I became a parent.