Frankly, it never would have crossed my mind that anyone (store owner, store employees, other shoppers) would care.

The notion that luggage is somehow improves the likelihood of shoplifting seems comical. Shoplifters want to blend in. Taking an usual item like a rolling suitcase into a store would magnify attention, making it harder to steal.

As long as there's no sign that prohibits items like backpacks, I wouldn't hesitate to wheel around your bag. It's far less conducive to shoplifting than big purses, baggy coats, or baby strollers.