Why a pack mule?

Answer:

The pack mule came out of Chris Taylor's frustration with never having enough space to pick up that last piece of treasure when playing RPGs. Instead he'd have to stop fighting, collect up all his gear, return to town and sell. Taylor's solution was to invent the pack mule, which will follow your party around and can carry up to three times the equipment of a person. If you'd like, you can have more than one pack mule in your party. The pack mule will even get tougher as your party levels, so he can survive some of the more dangerous areas of Dungeon Siege.