I still think the extra CPU power was mostly a side effect of the stable 3D (since it has to run a bunch of image recognition stuff at realtime) and not a focus for the New3DS. Though I'm not quite sure what the point of the platform would have been without it since the stable 3D was apparently a somewhat late addition; then again neither did Miyamoto.
Yeah, I wonder if it was more of a combination of a handful of items. Perhaps they were going to do a smaller CPU update prior to the Super Stable decision. Or not one at all.