I think you have hit on what I liked about Donna; she wasn't a little kid, but a real grown up and a proper match (but not at all in the romantic sense) for the Doctor.

We didn't watch much television at all when I was a child; there were only the two SvT channels (Swedish public service) available and they had only a very limited amount of children's programmes. Out of those, quite a scared my older sister in some way or other, so I think my Mum just decided against children's TV in general. So we mostly watched the news, mainly for the weather forecast, which matters quite a lot if you grow up on a farm.