Annan had indeed considered this possibility.
The Elves didn't dismantle the Curse Cellar simply because all elves had suddenly become enlightened, loathing the act of injuring the world through the use of cursed energy. Their civilization was indeed flourishing to the extreme, but that didn't mean their personal qualities were exceptionally high.
They chose to dismantle the Curse Cellar simply because the emperor of that generation was far-sighted. He judged that if cursed energy were to be used again, the unified grand enchantment might not withstand it... and the extracted cursed energy was hardly used to create powerful beings or for technological research, but was mostly used for various luxuries that served no meaningful purpose.
For the sake of their descendants, he decided to prohibit the use of cursed energy—those who touched cursed energy and were discovered could be sentenced to "absolute death penalty" at worst.
