The key here is the assumed supply issues.
Otherwise your argument and that of some others here seem to assume that there is no demand vs. price relationship, and that these cards will sell solely according to their relative performance vs. AMDs offerings. For devices such as this where there is no actual need other than upgradeitis, that is a dangerous supposition. For some I'm sure buying the latest and greatest is a compulsion (and I'm not joking here) but I think it's a fair assumption that the majority look at what they have and make some sort of cost/fun analysis and decide to buy or not based on that. Thus, unless you're supply bound, it will be a larger volume-and-lower profit/card vs. lower volume-and-higher profit/card balance to be struck. The problem with going lower volume-and-higher profit/card is that while it seems great, it reduces the total size of your market. The more extreme tech entusiasts will upgrade and the less extreme will tend not to. As long as the less compulsive wait around for the next round, all is relatively well, but if they loose interest in the whole thing due to lack of activity, you've managed to shrink your customer base and move deeper into a downward spiral, which interestingly can look fairly good on the balance sheet. For a while.
It would be interesting to see how volumes have changed, say during the last decade. I doubt we'll ever have other than circumstantial evidence.
You have to factor that they are targeting all segments of the market regardless the price point of an individual product. This hasn't really changed over the years aside from the low end where integrated has all but eliminated discrete products. You can actually get some idea of numbers if you look at market analyst (mercury or Jon Peddie) numbers which breakdown units moved for discrete and integrated.