Hunting... cats are excellent mousers and can be used for common household issues like having mice in your attic. So, which would be more useful? A dog that can hunt a duck, which will never find its way into your house or a cat that can hunt mice, which almost every house has.
Your argument about cats being easier feels like you're arguing about being a bad pet owner. You are saying that people who are lazy should be pet owners. If people don't want to own a pet because they don't want to take care of them, should they own anything at all?