I am pretty sure that someone from cdpr said during the E3 that they are still working on the engine. Creating tech demo isn't just to impress players, they wont get anything from it. Tech demos are created for sale purposes. Look at Cry Engine and few others.
Tech demos are usually filled with details and pretty textures, forest, jungle, water, space etc.
creating tech demo on the desert and concentrating on two average looking characters is just waste of money and time. You need to impress developers. This thing is some old CGI nothing else. Video isn't scaled properly, with fake PS4 logo in the corner.