The maps dont need to be bigger, you can see from one end to the other, if thats the way the map maker designed it , and if he doesnt want you to see a certain area, well , walls , houses , hills ect ect. These gameplay changes sure do give elevation a more important role, however, thats how i immagined true sight working, i.e giving elevated positions some advantages, foe example more chance to hit your target.
I dont know how its gonna work in coh2 but in coh1, as a map maker you had to be very careful with elevations. You could only vary them really over long distances. Otherwise you run into problems with AT guns hitting the ground a lot.
If you have Elevations changing only over longer distances than AT gun range, you have to limit line of sight, or spotting units etc become obsolete.
You can have realism in mods like Blitzkrieg, played by noobs, realism geeks and skirmish players, but not in competitive multiplayer