The model S is somewhat disruptive. It's closer to almost affordable(around $50,000 base price after US tax breaks) than the Roadster(which was $109,000 base). Very few people could afford roadsters. More people can afford Model S', but it's still out of reach for the vast majority. I would argue that the Nisan Leaf is MUCH more of a disruptive force, because it's relatively affordable(starts at $27,700), and is available everywhere.

The problem is that Tesla isn't trying to make a green box for the masses. They're making luxury cars, and charging luxury prices for it. That puts them in direct competition with companies like Porche, Mercedes, BMW, etc. It's not an easy market to get into, considering the competition, and the fact that the customers who can afford their products, by and large, aren't concerned about efficiency as much as they're concerned with luxury or power.