I'm unsure of the reasoning here. These are all vehicles for which there is great demand, and create a bit of a halo-effect for other models of the same brand. Every successful automaker produces "sports coupes". It's part of a full product mix.
Interestingly, the Camaro and the Challenger are both based on foreign platforms; the Challenger on a German Mercedes and the Camaro on an Australian Holden. GM has a pretty good vehicle mix, and one that is getting better. The Chevy Malibu (German Opel based) is a fine mid-sized car. That platform has spawned other sedans and small SUVs for the US market.
Chrysler has the weakest product mix, and simply made a good effort with the pieces they had.
Oddly perhaps, I'd say all three cars actually represent what the American automakers can do right. If all of their products over the last two decades were as well designed and constructed, and offered as much real performance (start, stop, turn, even good fuel economy considering the vehicle type), as these do, Detroit might be in much better shape than they are now.