Didn’t I Just Kill You Guys?
In my time with the alpha, both myself and several friends noticed that enemies in Destiny have a tendency to respawn a little too quickly sometimes. While this can work to your advantage when it comes time to complete a mission that requires players to kill enemies and gather the loot that is dropped, it can occasionally feel a bit frustrating.
This was especially noticeable in the alpha’s only story mission, where you could kill a rather strong enemy standing in the doorway to the first interior area, only to see him and his friends respawn after a few moments if you took too much time exploring the area afterward. And even when surveying the land in the game’s free-roam patrol mode, there were times when I just wanted enemies to stop respawning around me so I could take a look around and actually explore.
Personally, it’s my hope that the final game will limit story missions and strikes with a set amount of enemies, and patrol mode will see a bit more time between respawn waves.