I'm definitely overthinking this, but I think there is some pretty good literay meaning and symbolism going here even if Kishi isn't intending it.
Part of the significance of the War Arc seems to be that Naruto will finally realize the prophecy that the toad sage made for Jiraiya. This means that Naruto will be the shinobi to break the cycle of hate that has dominated the shinobi world. I think when viewing Kabuto using the Edo Tensei to fight against the forces of change to the shinobi system, this has symbolic significance when you think about it in this way. Kabuto is literally summoning the past in order to fight the change in the cycle of hatred. This could symbolize how the past is needed to be overcome in order to enact change in the future.
Another layer of symbolism is how the Edo Tensei summons have been defeated. Many of them have merely had their souls released from the ET from immense feelings evoked from their previous bonds. I think this is important to the symbolism because it shows the importance of how it is the past should be overcome. I think this shows that in some cases the past merely needs to be let go of and forgiven. I also think that the ET summons who are defeated by sealing could symbolize those aspects of the past which can not be forgiven, but must be worked out in the present.
tl;dr I think the overall significance of the ET being used to fight the Allied Shinobi forces is that in order to break the cycle of hatred the present needs to interact with the past in some meaningful way, and that the ET summons symbolize how the past interferes with the present to prevent people from moving on and creating a new world.