Covers, yes.
Cases, I beg to differ.
Cases might protect your back and sides from minor dings. Drop it on the screen though on something hard and not flat the glass can break. Who cares about minor dings on back.
Cases are a scam. Only since antenna gate and the free bumper case, people think they are needed. False. Waste of money. Adds weight and hides the good looks. Like buying a watch and then putting a bag on it.