They first "brought it up" when the show was commissioned back in 1963, and it's been part of the show's DNA ever since. Children grew up and stuck with the show, became fans, and retained 'ownership', which is why we still go on about 'our' Doctors years and decades after they regenerate. But it is a kids show. Sometimes it gets dumbed down outside of the family bracket which is when farting Slitheen and this happens...
Thank you again for the explanation. I have understood you already with your previous posts - and actually of course I know the difference.
But like I said: I allow myself to see it differently.