אשת יפת תואר Torah morality

In last weeks parsha (כי תצא) the Torah has the mitzvah of אשת יפת תואר. The mitzva can broadly be defined as follows. After victory in battle, a group of soldiers passes some locals, and one woman catches a certain soldiers eye. He separates from his fellow troops to gaze at her outstanding beauty, and decides to approach her. Before she is able to react, he forces her into an alleyway and fulfills his war-driven sexual cravings. Subsequently, he travels back to his native country with her at his side, and proceeds to shave off her hair, grow her fingernails beyond their normal length, strip away her beautiful clothing, and dress her in sackcloth. He lives out his daily life, returning to his family and friends whom he left for war, while his normal surroundings embrace an additional character: his captive. After thirty days, he forcibly converts her to his religion and marries her.

In 2017 this kind of behavior is simply not accepted and is in fact considered a war crime. And yet, the Torah permits it.

All kinds of apologetics have been written about this mostly saying that the Torah law was an improvement over what was the standard practice of war. The Torah at least provided some protection for the woman in contrast to the standard practices which provided no protection for the woman.

While this may be true, it raises major questions about the suitability of Torah to the modern era. One of the 13 priciples of faith of the Rambam is that the Torah laws will not be replaced. in other words, this law of יפת תואר was not only meant for ancient times but is meant for us as well. Clearly we have moved beyond this and this law is not relevant even though it was given by God. What does this say about the morality of the Torah? Could it be that modern society has surpassed the Torah in morality? If so what does that say about God's morality?