My guess is that the earlier closings are related to the lower crowd levels this summer... We went back in December the Week Before Christmas and MK closing schedule went from 9:30pm 3months out to 10:00 1month out to 12:00 2 weeks out. I am sure they are adjusting closing hours at MK based on the numbers of guests, Does it save them money? Absolutely. But it doesn't make since to keep everything open until 1AM when the park is only 1/4 full.
When we went back this July, MK park was no where near as crowded and they closed at 10... I imagine it takes a little pressure off CM's as well... especially since Pandora in AK has been staying open as late as 1AM all summer... obviously Disney is letting people check out the new land that they spent $$$$ on.
Its just smart business and Disney reallocating resources.