When you think about it, what Kyubee is trying to do is the exact oposite of the Anti Spirals. The anti spirals tried to PREVENT the creation of new energy in the universe. So... Magical Girls run on spiral energy? Makes enough sense.
TODODeygulash said: Only exception is here it's actually being analised.
Is it, though? I feel as though it was simply accepted by everyone (in the story) as a motivation, cruel as it is, and used as a plot device to transform Kyuubey into a "necessary evil" as opposed to just a manipulative jerk.
What the Incubators want is absolute grief. When there appears to be hope, but then you learn it is beyond your reach, that is when your despair is the deepest.
Little late to the party here, but considering that the motivation behind the Antispirals' actions was
stopping humankind's advances in technology and civilization due to the consequent increase in entropy and eventual destruction of the universe,
both they and Kyubey really both have the same goal in mind, just different methods.
Very different methods, though. Kyubey's method involves the sacrifice of the few to ensure the survival of the many. Yes, he was willing to leave one planet to its doom, but one planet in the grand scheme of things is meaningless if it ensures the survival of billions of planets, of which hundreds of thousands may harbor life.
The Anti-Spiral method involves mass genocide and oppression, essentially the sacrifice of the many to save very few, and the end of all evolution to preserve the universe. The question arises, why preserve the universe if it turns into a living hell for everything that resides in it? I think the Anti-Spiral is the greater evil here.