I think what bothers most people is not the HP differences but in what ends up being value differences.
Back in the day most manufacturers differentiated themselves with quality/safety advantages. Today everyone builds a great car.

With a supercharged Benz, or a Chrysler 300C your getting a good car AND a ton of HP - whether you can use it (or know how to use it or not). With Porsche, what do you get? You get a great car, but the value is where Porsche is losing it these days. Yes most of you can say that in a curve or on the track the Porsche wins, but how many buyers can really use that? The value for the Porsche's superiority on the track is there BUT no one (or at least very very few) can use that inherent value. So if you can't use it why pay for it?