Anyone who is ridiculing AMD for bringing great perf/$ is an idiot. Anyone that wants to argue WHY AMD is bringing great perf/$ is not an idiot but is equally attacked the same as the ones you suggest are attacking AMD for low pricing.
The why is linked. They need marketshare gains. That's their goal, read their investor briefing slides.
AMD made a bold claim to their investors, that they will return to the dominant dGPU marketshare player, over the next several quarters. You simply don't say stuff like that to investors without a credible plan of attack.
How do you steal back marketshare?
By offering an amazing product at a price that's hard to resist. ie. Lots of NV users may have inertia and avoid using AMD because of several reasons. But if it's such a good deal, that sense of personal greed will override those factors and they will not be able to resist.
On a related note:
Anyone who questions the profitability of selling a small chip, low TDP, GDDR5 product at $199 has no clue. Look at the GTX 960, did anyone question whether NVIDIA made profit at that price?
Basic maths with available figures: 232mm2, on a 14nm FF wafer that costs $3000, with yield claims of 0.2 defects/cm2, each cut-down Polaris 10 would likely cost them $25-30. Simple low TDP PCB, 4GB GDDR5, a low thermal blower and total BOM should be <$100.
Certainly not the margins of selling GP104 for $699. There's published material out there, only 15% of GPU sales are above $350. Of this 15% segment, the vast majority (AIB claims ~85%) are $350 to $450. Meaning GPUs above $450 make up a very small volume of the overall GPU market. Thus, these mainstream GPU make up for lower margins with more volume.
I mean it's not a shocker and it's quite silly to have to say such obvious things but sometimes people on this forum have strange ideas that GPUs can't be sold for $199 as it's not profitable.