Some of the screenshots at IGN and Gamespot are set-scenes, where the BHG/ES folks made a Pretty Scene and took pics of it. These are not representative of the game's regular maps.
For one, flatter maps = smaller file size. A lot of landscaping/elevations changes = a larger file size for the same AREA of map. Where random maps are concerned, the random map script generates the elevations on the fly, so a map with a LOT of high mountains/deep valleys will lag in multiplayer online. Some of this may be due to the complex Physics Engine of the game, which calculates animations based on laws of physics and terrain properties. Other times it is due to some players' graphics settings - smooth rendering for wildly erratic elevations can be demanding on the connection.
So the maps you get in TAD for skirmish and online play are flatter and simpler to minimize lag and optimize performance.
The exception to the rule seems to be that cliffs are less laggy than rounded hills. The reason is probably because a cliff has 2 main elevations, a base level and a plateau level. Only 2 different numbers to calculate for the computer to represent a cliff. Rounded hills on the other hand, have a multitude of different elevations at various points on the curve of the hill. So there's more numbers and slopes to calculate.
Crunkatog on ESO
Bart331 balance suggestion: aztec: remove civ
Voltiguer: Ender, Sioux in 1.04 will be a top civ, no matter how many layers of Sioux goggles you put on
schildpad on Elephants: ...their mansabdar unit sucks so hard it looks like a black hole
Crunkatog on Steam.