One of the rare issues in which there is no dispute between Muslim scholars in regards to abrogation is that the Quran has abrogated all previous scriptures and religious laws.
Jamaal `Ataaya, in his book حقيقة النسخ وطلاقة النص في القرآن, supports that too but he takes issue with scholars views (e.g., Az-Zurqaani) that prior scriptures and laws were not meant to be lasting or universal and that's why abrogation is possible. On page 97, he considers that an insult to God's wisdom. He adds that prior scriptures contained all the values contained in the Quran.
He stops short, IMHO. He says that prior scriptures were incomplete and that the Quran is the complete scripture. He cites the famous completion verse, 5:3, and the hadeeth of the Prophet (PBUH) in which he gives a parable of a beautiful building that is missing a brick. People who look at the building keep admiring it but say, "If only that last brick would be laid!" The Prophet (PBUH) said, "I'm that last brick. I'm the last of prophethood."
Indeed, the Quran is complete and final, but I respectfully disagree that prior scriptures were not complete. My evidence is that God called the Torah "Complete" and "detailing everything" in,
So, the Torah was complete and could have been final. But what happened? The Jews edited it, removing, changing and adding to it. So, it was lost. They took the divine and ruined it. That is why God sent Jesus, peace be upon him, with the Gospel, to abrogate the Old Testament and restore the Torah. Then what happened? The Church did to the Gospel what the Jews did to the Torah.
That is why God removed His trust from the Children of Israel and gave it to the Arabs. The Children of Israel were not trustworthy and failed to uphold their end of the covenant, which is to believe in God and His Messengers and follow them and not treat scriptures like a commodity.
So, God knew that the Torah and the Gospel were not going to last, but it wasn't because they were incomplete, it was because people were going to mess with them. He revealed the Quran to abrogate the Old and New Testaments and restore the Torah and the Gospel. And this time, He preserved the Quran Himself. That is why the Quran is final and cannot be abrogated. In fact, the very fact that God vowed to preserve the Quran Himself and did so is testimony that the Arabs would not have done it themselves. Sure enough, no sooner than the Prophet (PBUH) died, Muslims started claiming verses of the Quran abrogated!