Enreal Engine in fact use lot of tricks
For example in some games (Last Remnant,Gears of War 2) :
they put some walls with a very not detailled diffuse map for color variation and they apply a detail texture for the normal map.

But integrating lot more things from a modeller to an engine by plugin (import lights, paths, effects, anything else) make more work in each plugin and more dependant the engine to the modeler !