I am sure that the 4 cylinder cars have lost some parts of the market that were probably more purist, but they have opened up other markets. For instance there is market that like to tune cars, and there was not much you could do to improve the power of the 6, but the 4 is begging for it. Easy to make big gains with minimal outlay. There will be many upgrading from more traditional Subaru/BMW turbo markets into the entry level Porsche sports car market.
I personally have come from previously tuned Subarus/BMWs. I love the handling of the mid engined Porsche, but I was struggling with the idea of buying a beautiful looking car that would struggle to accelerate faster than a sports oriented family wagon. The turbo 4 fixed that. I really love the sound of the 6, but the 4 sounds great also... in a different way. If like me, you appreciate the sound of a nice Subaru, the Porsche sounds different... but in the same vein. Certainly it sounds good enough that you would not consider losing the performance just to have a small improvement in noise. Of course many who raise their nose to a Subaru would not agree!!