The no respawn is the reason their random loot on mobs does not make sense. The reason for diablo style loot it to go kill respawns over and over looking for better loot. I also hate the no respawn clear without consequence. It should not make you a hero, it should make you hated as the towns people see live stock over populating, crop production go down from overgrazing and eventually a famine because the people can no longer feed themselves or their live stock because you killed all the mobs that would help keep those numbers down in the first place.

When you talk to the orc on the beach he even says we will not stop trying to come and take the stone in the city. Yet no more waves come, at least if there was respawn it would make sense with the dialogue they have in place. You are not even the one that cleared out those orcs and it is indicated they are willing to keep send wave after wave.