In terms of PS4, the picture has definitely gone from one of very simple 'cleanliness' to something more complicated.
Thinking of the 18 CUs as one entirely unified block, it was easy to see 'freebie wins' over Durango with relatively straightforward approaches.
But if 4 are taken out of the hardware-balanced regime, devs won't be able to just twiddle a few lines of code to get better AF or whatever out of purely having more grunt. It'll take more thinking, it adds programmer burden (for the benefit of, presumably, improved performance and control if you do want to go out of your way and use your GPU for things other than graphics).
Getting high utilisation out of PS4 will require less naive approaches now too. It makes me go 'ugh' wrt simple development while raising an interesting new prospect for devs that want to get every last ounce out of the machine...they'll now have to think about fairly substantial gpgpu work, and that'll be interesting to see.
I still think Durango's approach will be less forgiving of naive approaches though. If we consider the ex-compute GPUs and CPUs (more obviously) to be basically a wash now, it still has a more complex bandwidth and memory setup.