Except for the fact that it would absolutely destroy the consoles. I understand what you are saying, APU was the way to go but for similar performance the comparison (if you are using maxwell which wasn't out then) would be a i3 type CPU and a 750 Ti.
Which is worst than what ps4 have.
750ti is quite a bit slower than 7850, which is slower than ps4 APU.
8 jaguar cores are great for consoles. 2 cores are relegated to background tasks, while the rest is in 100% dedicated to game. Would you sacrafice 1 of 2 cores of i3 to background tasks? It would be a waste.
2 heatsinks or heatpipes, two memory pools without hUMA, less compute performance that developers start to use. No dedicated integrated sound processor. This all adds cost. The logistics with two dies is a hassle in itself.
I think the consoles are great for amd. Possibly amd pushed for more jaguar cores, rather than less BD cores to force developers use more cores, which will affect competitiveness of their CPUs - FX8350(8T) vs i5(4T) and FX6300(6T) vs i3 (4t).
Also, putting more emphasis on GPU than CPU will hurt intel more than amd. People will not have to upgrade to new CPUs so soon and if they will, even low end stuff, where amd competes is sufficient for gaming.