It would seem they are a luxurious and elegant, and support a clean-energy environment for the future. While it might not appeal to even the mass luxury-vehicle market, if people are willing to pay the price and believe in electric cars, then it is worth it to them. Quite simply 'pay what the market will bear' applies, as always.
First or all, I don't think the car in the picture is a Tesla, but that is besides the point. Yes, they are expensive, but they are unique, luxurious, and may eventually have a virtually infinite battery. If all goes to plan, Tesla will have a TON of supercharger stations (http://www.Teslamotors.Com/supercharger). And if you have that many, will the battery life matter that that much? Also, Teslas are the only car that have a 17" touchscreen control display, and if you look on the website, they look quite sleek and can be customized to an extent. I think there is enough going for the car to ask for the price they do.