I had a first-gen Miata. It looked great and handled well but it was quite impractical. No back seat, tiny trunk, and not even a powerful engine to get excited about. Then I moved to snow country where I could only drive it half the year because of its real wheel drive. Now I have a car that looks rather ordinary, has a huge trunk, a real back seat, four wheel drive, and which can easily cruise at 140 mph if I'm stupid enough to want to do so. The stealth approach is better for me.
Sure, a small sports car is less practical than a big one. But sports cars exist, so that is irrelevant to the whole question; clearly there are some people who don't want a big, ugly car.
By analogy, Asus (and several other brands) now makes laptops that look almost exactly like a MacBook Pro — unibody aluminium enclosure, glass screens and everything — at a tiny fraction of the price. So why won't anyone create a Porsche 911 replica that is as good-looking and as good to drive, only without the insanely high price?
I was trying to answer the question from my perspective but I did a poor job.
Impractical cars exist, but they sell in low volumes, so they have to be expensive because the tooling for any car is horrifically expensive -- much more so than for a laptop computer. A cheap 911 clone cannot exist because the body style is too impractical to sell in high volumes.