I have never worked as a cashier, but I can't imagine it's a very fun job. Automating out those jobs seems like a win-win, as long as the former cashiers can find a job doing something else.
Edit: For anyone wondering where my perspective is coming from, see this: http://www.businessinsider.com/amazon-go-grocery-store-futur...
Stacking the shelves isn't anymore fun that working the checkout. As someone who has done both I'd say checkout is the preferred role as it's much less physical (stacking shelves gets tiring after 8 hours) and you get chat to customers.
When I was talking about the other jobs at WF I was thinking about like.. the ice cream scooper, and the smoothie maker, and the customer service rep at the front for when people want to return items. That's not to mention all the the chefs that make the food for the hot bar, or the bread and cookies for the bakery department, or the sushi. All of those jobs could have a social element to them.
Contrast that to other grocery stores (Shaws and Wegmans, for instance) that seem to calculate exactly how many cashiers they need such that no line is more than 3 people deep, but none of them are idle, ever. And the average cart is full-to-the-brim, so there's always a wait. It can be 9pm at night with 3 customers in the store, but there will still be a wait.
A locker would get me into Whole Foods more often for sure.
It's like how Mark Zuckerberg launched Facebook, except for if he had just bought Harvard.