Probably cost. Single cast-aluminum parts are cheaper than assembling a fin stack.
I'm glad they got rid of the yellow slots/ports. I didn't mind the gold on the heat sinks--X79 Deluxe looked good--but the day-old-urine color of the plastic components bothered me to no end.
Interesting to see a circular design motif, though. And how far does Asus plan on diluting the ROG line? I want an Extreme and a Formula, not a half-assed black-and-red Ranger.