Battletech, fantasy and the technological arms race

One thing I find interesting with Battletech, is that there are different levels of technology in the setting, and they all fight over technology as much as for power for its own sake. Sometime an influx of new tech shakes things up a bit, and it influences the capabilities of the other states and factions involved in the conflicts. Why aren't we seeing this in the fantasy worlds of roleplaying?

Imagine a country, which have invented gunpowder or the printing press. They invade another country and suddenly that country is filled with guys with primitive guns. Later on another country creates the telegraph and suddenly the game world have "instant" communication in some parts.

Imagine how cool that could be. Imagine your characters in the midst of it.

I think that part of Battletech could be imported successfully into your fantasy campaign!