in a way, it explains why so much of the genre output in years has been so innocuous, since doctor who was a kids show. in fact, doctor or no doctor, the majority of genre work is either a kids show or aimed for teens. there is really no adult genre work out there than springs instantly to mind--well, actually, that's not true. a few movies, some books, but they too suffer from often being aimed for a teen audience, and being so bland that you could swab vegemite over it for a good little taste. but the majority of it is aimed for kids, and that, perhaps, is its greatest failing.
and certainly, in a unconnected way, the doctor is a nice symbol for that.