It's a great feature. I can't tell you how many times I have seen trip and falls where people are trying to pull two or more pieces of luggage in separate hands... not to mention holding up the flow of traffic in the concourse. What's worse, people try and haul it all up or down the escalators. For some reason, when luggage gets stuck people don't want to let go... not realizing they will get yanked back and fall, usually onto the person behind them, who also falls and usually sustains lacerations to his or her head, arms, face, etc.
Not a great way to start or end a trip. We have a travel rule, one suitcase and one backpack for carry-on. Always leaves a hand free for handrails, etc.