Totally superficial film judgement

I've not yet seen the new Pride and Prejudice film (but hope to soon) but I have seen the trailers and something is bugging me. If you look at these publicity shots you might (or might not) see what I mean. For some reason the two leads Keira Knightly (Elizabeth Bennet) and Matthew MacFadyen (Darcy) just look too modern. Something about their hair and faces seems to speak of the 21st century rather than the 19th. Does anyone else see what I mean?