I believed it was supposed to be aimed at a Family audience , mary whitehouse complained about the suitability for children in the 1970's hence my opinion it was for adults but kids could enjoy it.
i think as the 1970's and 1980 series went on it went more and more for the children audience and now it is firmly a kids program.

The techno babble has lost all sense of being half true and is dumbed down with the doctor often now being more magic than scientific.

maybe i am being a bit too harsh .