Because we're programmed to be protective over young... Though infanticide happens. They are clueless and physically vulnerable, and I think asides from the instinctual part, people are consciously attracted to that honesty. Like animals, little children are going to be be the most honest, or mirror-like living creatures you will encounter. There comes an age where all seems to be surrounded in deceit and fakery.
I feel maternal all the time, particularly in the winter. But I'm a wolf therianthrope- I feel like I should be rearing puppies. Not in an 'I want to pet them' way, but I want to be teaching them how to be with other pack members, howl, nurse them, groom them etc. I still get extrememly distressed and depressed at times when I feel I'm not 'fulfilling my purpose' In equivalent wolf years, it is mommy time and I do find myself looking at the landscape for potential den site, wondering why I don't have an undercoat to line such a den with etc. I don't really want babies at the moment, human babies often disgust or frighten me but I'd probably like the idea in the future. That being said, my mama had me at the age I am and I like our age gap.
It's crazy, I'll have periods where all I think is puppies, puppies, PUPPIES!!!! *frantic circles*