Or maybe it can, it just chooses not to. Whatever the facts, Moffat Daleks have inherited the biggest flaw of RTD Daleks, which is that they only exterminate the unimportant people, for no other reason than Plot.
In days of yore, the Daleks were frightening in part because all the actors acted as if they were frightening. Especially the Doctor, because he had seen their bad side once or twice before. We the viewers knew they were touchy inferiority-complex ridden psychopaths with hair-trigger death rays and we held our breath whenever it looked like one of them might get more than slightly grumpy, because we knew someone was going to get it.
Almost always, the Doctor sidled into their foul schemes undetected: they had invaded or annexed somewhere for their own nefarious purposes, often making an alliance of convenience with the worst examples of humanity which would all end in over-exposed negative-effect tears, that being the best effect the Beeb had in those days for death rays. Somewhere along the way there would be a slightly potty scientist who begrudgingly, reluctantly came over to the Doc's side and probably paid for it with his life.
Of all the New Who adventures to date, Victory of the Daleks really was the one that would have benefited most from the old school 4-part, 25 mins each treatment. It bore a strong resemblance in places to Power of the Daleks, an adventure sadly lost to the video archives but still available in audio format (which is how I first heard it), and could have learned from it. In that one the Daleks also ingratiate themselves into human affairs, aided by the worst examples of humanity for the latter's political reasons, and of course it all ends in over-exposed negative-effect tears. With Victory of the Daleks in old-school format, the Doc would take at least two episodes to establish his good guy credentials, with even (or perhaps especially) a highly sceptical W. Churchill ranged against him while all around him strange things were happening that the powers that be just didn't get. He would have been incarcerated at least twice. Those two eps would also have been used to establish the spin-off Dalek tech also in use by the British during WW2. And there would be extermination, left, right and centre. It would start slowly, mysterious death by mysterious death, with victims gradually increasing in importance.
Maybe the cliffhanger at the end of part 2 would have been the veil of niceness being withdrawnand the pepperpots revealing their true colours, about to zap the Doctor. Though to be honest it could have been spun out to the end of part 3. Instead of zapping two extras, as shown, the Daleks would turn their guns on the entire British high command, Churchill included, and it's in saving them that the Doctor proves his point.
Part 4 could go pretty well as the rest of last night went, except that if the Doctor simply had to have a long talk with them, he could do so from within the safety of the TARDIS forcefield.
And the potty scientist would have paid for it all with his life.
Let's not do it down entirely. There were some good lines and an especially good portrayal of old Winston. The new Daleks look funky and hopefully will revert from now on to suitably Dalek-like behaviour. Indeed, the whole concept of WW2 Daleks in olive green, offering cups of tea, was wonderful. It's shame it was dispensed with in the first ten minutes.
It's also a shame we never got to see the answer to the biggest question of all, which is how exactly does a Dalek take stuff out of the webbing pockets around its waist? The most logical solution is that they pair up and take stuff out of each other's pockets, which is a bit too like a party game to be all that serious.
- Update: see here for unkind but funny speculation about the nu-Daleks.