Well y'see, they made the player models smaller, to make the maps larger. Or at least, seem that way.
They did it on 1.0, it seems, and they've been smaller since.
The end result is... well thaere are several results. One, is that maps seem immensly huge. 4 times so, as been said. Another result is that maps need to be specifically tailored to ESF. If not, the models seem to float a few feet off the ground. ...Load a regular half-life map in ESF, and you'll see what I mean. Another result is that models also rapidly shrink with distance, due to the change in size and perspective. So that models are dots in all but the closest distances.
It also gives the models a naturally sharper look, since the textures don't need to be stretched as much.