The reason is two fold. One is that they think that American tastes in design are different than in Europe. Yes, they think that Americans would prefer to drive this:

over, say this:

Though I'd love to have this:

The second reason is that they don't think Americans will pay very much for a small car. In America, small car usually equals cheap car. It doesn't matter that European Focus has more features than say a loaded Accord, it's a small car and thus should be dirt cheap. Cars like the Mini have shown that
maybe that perception is changing, and that Americans would be willing to pay higher prices for a more premium small car.