Death and death penalties in games is a balance in terms of design. Diablo II had you loose all your carried money, and all your gear stayed on the corpse. You lost a percentage of experience, and could in fact even loose a level. If the corpse was not retrieved, the items were lost. Then again, death penalties in odler games are usually quite much more harsh than modern equivalence.
Death Penalty in Diablo III
The following was said by Jay Wilson on death in Diablo III:
When a character dies, will it lose gold and experience like in Diablo 2? Jay Wilson: We have not actually decided on the final death mechanic. I can guarantee that you will not lose experience. We are not urging to big penaltys for death. But we want enough of a penalty to be there, so that death has meaning! Like to lose a little bit time, some kind of decrement... We do not currently have a durability, but some kind of ... a gold cost is actually not so bad. And having the player to waste some time, that is certainly an element. Generally we kind of rely on the effect that players do not want to die. You know, you just do not want to. So there is no real reason to add a further "ding" to them for something happening that was already unfavorable to them. But we have not got our final mechanics on that, yet.