I see your point and I agree with you how these sport pickups do compromise their utilitarian nature, which almost makes their purpose self-defeating. But the thing is, the US is FULL of people who absolutely LOVE pickup trucks (i.e. white trash, etc.), and for around $50K they'd rather ride in an American sport-pickup truck that's fast as balls (assuming they don't need all the utility of a pickup, but instead prefer the look and feel of it) as opposed to an M3, for example.
You have to keep in mind that the Ford F-150 is the best-selling vehicle in America, and has been for like 10 or 15 years or so. Based on that kind of demand for pickup trucks, the SRT-10, F-150 Lightning, Chevy SSR pickup, (etc.) are guaranteed to be worthwhile for Ford, Dodge, and Chevrolet.