We've only been on 2 cruises so far, spaced 2 yrs apart, so we've gotten 1 sling bag so far. I like the sling bag, I used it for a girl scout overnight at the Museum of Science to carry the troop first aid kit, my water bottle, and paperwork. It's not meant to be a beach bag, it's a day pack to carry the essentials in. At the Disney parks, they sell sling bags for $28...yeah, it cost much less for Disney to buy them, but it's the perceived value of an item.
For frequent cruisers, maybe at the Gold level and higher, they should give you a choice of items or let you 'decline' the gift for something consumable--be it bottles of water, 'free coffee/tea' tix for Cove cafe, a snack item, whatever.