Well, was magic invented yesterday?
The typical D&D world is old. A world that can measure it's age in elven or dragon lifetimes is old enough to evolve. The typical D&D world has seen stone evolve into bronze into iron into steel. It saw wood armor be replaced by chain and plate. Barter was replaced by coins. It saw the rise of crossbows and even firearms. Yet while all this was happening, no spellcaster, hedge mage or priest thought to begin large scale production of magic lanterns?
My point isn't that a D&D world will become Eberron one day, it's that it should be there NOW.