A feature I actually would like to see removed

[bobbin]

I think spies and watch towers are abstractions of more exstensive surveillance networks hence their large line of sight. Also in reality armies didn't march blindly into enemy territory they would always send spies to scout out the land ahead and certainly wouldn't just stumble across a huge city the way you described.

It would be great, if there was a feature in the TW games that didn't even let you see the whole map!
Kinda of a Age of Empires feel, when you had to take a scout to find the borders of the map. Here of course one would know how the EB map looked, but not precisly.

If your meaning a completely black fog of war where you can't see anything then you get that in M2TW (it covers the americas).