Comment by hinkley

It’s been adopted in game engines to handle story logic, so the people writing the game can be decoupled from the people writing the engine, and don’t have to code in a low level language against a constantly moving target.

And I would argue that a lot of the staying power of World of Warcraft came from the Lua based addons democratizing the UI. Blizzard co-opted a lot of features from best of breed addons back into the base game. (That and negative pressure in the economy to keep from having every new character wielding the third best sword in the game due to deflation, but that’s a story for a different thread)