I honestly think they should add a penalty: If before you die, you took damage from an enemy's direct attacks every 15 seconds , you drop all of your items besides armor. Keeping armor ensures that they can still survive possible spawn killing and either be able to grab gear from a chest or to effectively annoy opponents breaking blocks. Dropping all the items can make defending the wither more difficult making a need to balance defense and offense, also encourages using the golden apple more often since you don't get to keep them after death. Chests are supposed to be defensive items and they are currently quite useless.
(you must be attacked by an enemy EVERY 15 seconds before dying. During any moment of your lifetime did you not take damage from an opponent for 15 seconds, you keep your items on death. This effectively prolongs spawn time as people may choose to get out of danger instead of fighting their opponents directly on spawn.)