The obvious reason is because they are overpriced. And now they have made it even worse. This does not make much sense. Hopefully manufacturers like Asus can step up with even better quality Zenbooks and do not join this 'premium' binge.
It seems the 'premium manufacturers' see this as a non-elastic market and want to take the prices to around $2000. But is there enough differentiation in laptops beyond the screen and build quality to justify that premium. Everything else is off the shelf components and these dual core chips just don't seem to be worth this kind of money.
Even 'premium' phones are becoming dramatically more expensive with every refresh that are way out of sync with component prices.
But once you notice Windows 10 S, then the price is unusual. I bet the hardware team is disappointed by that decision for this machine. It doesn't make sense.
And free updates until 2018 doesn't help tbh.