Because some people, like me, never learn how to drive sticks.

I don't mind "boring" drives; I have enough adventurous drives on I-40 that I don't need the "thrill" of adding stick driving to it.
Frankly, I'm glad that automatics are as common as they are, given the popularity of cell phones. If one hand is holding the cell phone up to the ear, and another one is shifting gear, how is the person steering? lol
I agree with some of the others as well. DH had a manual-transmission truck when he first moved here. Two months of sitting in Nashville rush-hour traffic was enough for him to trade it in and get an auto-tranny vehicle.
As long as you drive sensibly, auto-tranny cars don't use up that much more gas than manual ones. I try to speed up and slow down gradually and rarely go over the speed limit on the interstate, much to the chagrin of the NASCAR wannabe drivers around here.