It's For Children.

Whilst I agree with whoever it was that described Stephen Fry as "a stupid person’s idea of what an intelligent person is like", he's not wrong here:

: 'It's just shocking. The only dramas the BBC will boast about are Merlin and Doctor Who, which are fine but they're children's programmes. They're not for adults.

Exactly right. I saw adults complaining that the new Dalek design was obviously aimed at children, to which the only reasonable response is "well duh". The only occasionally adult aspects to the show are when the writers try to shoehorn in unsubtle political propaganda.

There are very few high quality programmes aimed at adults on British television, particular with dramas.