While I do not know factually I strongly suspect D:OS level system does not support respawning (or more specifically infinite exp from respawning). Just because a game does not have respawning does not mean it cannot have a certain amount of randomness (as well as branching story arcs) that support replay. One game that I enjoy (and played many time) that has no respawning is king bounty legend (and crossroad).
On the other hand a game that I enjoyed (and played many times) with respawning was titan quest (or for that matter wizardry 8).
Both systems can work quite well.
