In an article for Va'eira, 5773, Rabbi Cherki explains that the Ten Plagues showed Pharaoh that G-d is the master of the world and therefore the Divine command to free the slaves and let them take charge of human history was justified.
If we ignore the blasphemous aspect of Pharaoh's demand – "Who is this G-d whose voice I should listen to?" [Exodus 5:2] – we must admit that his declaration is quite logical. After all, Pharaoh held a responsible position the likes of which had never existed before his time. He was the leader of the most progressive culture of ancient times, which would establish the dominant direction of all the history that would follow. And Moses came to him to demand that Pharaoh give up the economic basis of the Egyptian empire, the slaves, thereby leading to economic and political collapse. Even worse than this – the slaves would be the ones who would lead the progress of mankind from then on. And Pharaoh was supposed to accede to these demands merely because Moses spoke to him in the name of an unknown G-d. Indeed it was very reasonable for Pharaoh to ignore this demand.
Pharaoh's reply was as follows: I will accept your demand if you prove to me that it is correct. What is needed to do this is for G-d to be revealed to Pharaoh. And that is indeed what was accomplished in the process of the Ten Plagues, whose stated purpose was that "Egypt will know that I am G-d" [7:5]. Egypt and not Bnei Yisrael were the main objective of the revelation.
The Plagues emphasize the unique position of the nation of Yisrael as opposed to Egypt in order to justify the demand for Egypt to give up its position in the history of mankind. The Plague of Blood, which damages the great natural force upon which Egypt is based, the Nile, does not harm Israel. This demonstrates the capability of Israel to overcome natural stumbling blocks, a skill that was acquired from Abraham, who "crossed the river" to the other side. The Plague of Frogs is based on a being willing to sacrifice – the frogs were willing to enter hot ovens in order to do G-d's bidding - and this is characteristic of the tradition of self-sacrifice that Isaac taught the nation. The Plague of Lice, which demonstrated the power of G-d in that demons were not able to control even such a tiny creature (Rashi), is based on the power of Jacob, who was given the title of "G-d" by the Holy One, Blessed be He (see Megillah 18). The unique status of the Children of Israel is a result of the traits that came to them from the Patriarchs.
However, it is still possible to claim that in spite of their unique traits, when they went down to Egypt in the days of Joseph the nation of Israel agreed to combine their experience with that of the Egyptian nation. The reply to this claim is that the Hebrews maintained a separate cultural existence when they were in Egypt, and they dwelt in the Land of Goshen specifically in order not to mingle with the Egyptians. The proof of this idea was the Plague of Wild Animals, where Goshen was kept separate, "where My nation dwells, and the wild animals will not come there" [8:18]. That is, this was done in such a way that Egypt and the Hebrews did not mix together.
One might still try to claim that since we are all human beings we must continue to participate in the same historical processes. The Plagues of the Epidemic, Boils, and Locusts, which harmed Egypt and not Israel, occurred because of the ethical downfall of humanity in the murders of the generation of the Deluge. In addition, the idol worship in the Tower of Babel was symbolized by the throwing of black soot towards the sky in the Plague of Boils. And the illicit sexual behavior of Sodom was punished by a mixture of fire and water as in the Plague of Hail, where fire was mixed in with the hail. In summary, the Plagues demonstrated the ethical gap between the nations of Israel and Egypt.
Source: "AS SHABBAT APPROACHES" – a biweekly column in Shabbat B'Shabbato, Va'eria 5773, Volume 1457. (Zomet Institute) See:www.zomet.org.il/eng