I am not sure why female companions should grow in any particular way in Dr Who. I think the idea of a savvy companion is much better suited to today's world. I thought the female character in Blink would have made a great companion. Sure the places they travel are new but I think with the proliferation of sci fi, in our world and presumably the Dr Who universe, any modern-day companion would handle travel through time and space much better than ever before.
To keep it in the Dr Who universe, it is not like the citizens of the Earth have never seen aliens- 20% of the episodes from the last 3 seasons had aliens landing/crashing onto the earth in plain view, anyway...
and, Dr Who's philosophy has not really changed in years- he has always been "progressive" and small 'l' liberal.
(hopefully this will not turn into a political debate.

)
i have more of an instinctive problem with a 22-year old actor as doctor who but cannot wait to see how they both go.