It's a test right now, but it seems to indicate to me that they are concerned about prebooking availability for those rides. Maybe they are thinking that if you are staying there a week, you would probably spend two days at Epcot to see it all anyway, so if they break those two rides up, no big deal, you just ride the other one the other day.
I agree with you there. I still think they are weighing all of there options yet tho.

Although I think everyone will still choose TSMM. But it would spare some availability at either ToT or RnR to do the same thing there. I think if they felt the need here, they can't help but feel the need there as well.