The main benefit for me is that because most people are afraid of them or don't see the benefit, the line is shorter. When the regular line is shorter, I still use them.
This is probably a style thing - I shop 3-5 days a week on my way home, which means I never buy more than a bag or 2 of grocs and the automated machines are always faster. It also keeps things lighter on the walk home, and food fresher.
This is probably not a choice i'd make if I didn't live in a city and commute by bus and bike.
