The globe would be fun, I mean, it would have the ultimate realism. But, I don't have 80 year to render it and create the cities, like New York, Boston, etc.
There just isn't enough time to create it all.. Plus, if you wanted it freeware... Well, get ready for some crappy textures/terrain.
People don't have time for the whole world.. I am sure in the future, if they keep updating this game's engine, people will have more time, or rather, better CUP's and smaller rendering times.
-PonY