Obviously Jpeg compression chip is so cheap (every digital camera has one) and necessary (you can't have a RAW only camera). Lossless compression chip is another story. The algorithm is completely different than lossy Jpeg compression. Obviously, Pentax CAN put in such a chip into K10D. Pentax CAN ALSO put in a TTL flash sensor so that it can take TTL flash. And Pentax CAN ALSO pack in a lot of other features that's only available in cameras like D200 and Canon 5D. But the bottom line is Pentax needs to price the camera to compete and need to decide which feature they can omit without upsetting potential owners. If compressed RAW is very important for you, go buy another brand that fits your need.
Canon Rebel 300D/350D/400D never offered spot metering feature (an important feature for the operation of the camera IMO) and yet it is still the most popular camera on the market.