Please think of those with limited Disk Space and those who will download it from Digital Distributors
Or how do you want to have historic accurate Province Pictures with that long timeframe?
So what if they need to download ½ or 1 hour longer. And who still goes on computer made from the last century?
Well most of the towns have the same buildnings in both world wars. (Brandenburg Tor, Big Ben, Hagia Sofia, The Forbidden City and so on).
Of course it will be hard to find pictures for some desert provinces or Siberian provinces but of course there it can be same landscape picture.
I don't think this would take a lot of space if they are in the best picture formate.
