It's more about whether the ideology of that empire infiltrated your subsequent historical narrative.
Western culture is built on the results of the Greek and Roman empires, the Catholic Church, the English (and French/Spanish/Portuguese/Dutch) empire, and the American conquest.
No one is the villain of their own story. And these empires - not the Persian, Ottoman, Germanic, native American, Russian, and other empires which opposed them, or the Chinese, Japanese, and Mongolian, and other empires which didn't feature in their storyline - wrote the storybooks.
It's the natural way to judge things - perhaps not the most accurate or honest, but those take a lot of effort to establish.
