The judges should mark what they see in front of them, and also what they don't see in front of them (if they should have seen it). Why should lifts that they haven't done before be judged any differently to steps or dances they haven't done before?
If you do difficult lifts well, you get better marks. If you do difficult lifts badly you lose marks. If you do easy lifts or no lifts in a dance where lifts are expected, you also lose marks, but as many as if you made mistakes? There's the question!
It's also a bit like diving - the mark you get is a combination of how difficult was what you attempted and how well did you carry it off. And that's the balance the pros have to try and strike. Mistakes lose you marks, but so do dances with little content. but the public might not see the lack of content but may be more likely to see a mistake. Difficult decisions. ..