All of the following is just my own opinions.
-Introduces new player to the necramech system. (well any new players from when necramechs are added onward)
-Gave players a second chance at scarlet spear rewards.
-Introduced players to a new version of an existing mission type, endurance, where you just keep going until it gets too difficult. (most would say that this is just disruption mission, and they're right, same concept here, different execution)