That’s a question that has resurfaced, and that will probably not go away. The same thing was discussed when the architect cert was first announced back in 2009. If you follow the comments you’ll see that it was exhaustively debated, and it was even botched in the news that either CCIE or CCDE would meet the prerequisite for the CCAr.
I absolutely agree with splitting implementation/config/troubleshooting and architecture/design into separate branches, but the pyramid should be changed to reflect that. Architect in the pyramid sits on top of Expert, which includes CCDE as well as CCIE. It doesn’t make sense to me for CCAr to sit on top of the CCIE if it isn’t a prerequisite for CCAr. If you have two pyramids, with CCAr on top of one and CCIE on top of the other, then no feathers are ruffled.
When it comes down to the question itself, I agree that CCDE is the prerequisite for CCAr and not the CCIE. The separation of the design track is there in the industry, and it doesn’t make sense to exclude a qualified architect that doesn’t have a CCIE. It would make no sense for them to have to go back and obtain CCIE to be qualified. Also keep in mind that CCDE and CCAr are vendor neutral for the most part (EIGRP on the CCDE the exception), while CCIE requires expert level skills specifically around configuration and troubleshooting of Cisco products (hardware and software components).
Someone at Cisco Live said that it’s no longer a pyramid, but it’s more of a tree. If that change is made, then one has to assume that something new should now be on top of the CCIE as well. Before the CCAr was announced, there were rumors of a “Super CCIE” cert that would cross multiple tracks and would require multiple CCIEs as a prerequisite. That would be pretty cool, but I guess for now we have to live with CCAr sitting at the top of the pyramid over Expert – over both implementation/support and design branches.