First, just arguing prices is how the PC industry got into trouble (commoditization), and how Apple became so huge. Customers are obviously willing to pay for premium devices, allowing for actual profit to be made. The Ultra books you linked to can't begin to be compared to the Surface quality wise.

Second, ignoring quality, those devices are lacking features. Better screen resolution and viewing angles, touch screen support, sensors, etc.

The Surface Pro provides tablet functionality (not found in your Ultrabooks), pen input (not found in your Ultrabooks), quasi-laptop functionality (your Ultrabooks will do better here), and full desktop functionality via docking (works for both). None of this may be compelling for you, but if you can't see why it might be compelling for someone else...