[Ha-Rav's Commentary on the Haggadah]
Question: Couldn't Hashem have redeemed the Nation of Israel with one plague?
Answer: Of course! Our Sages already asked: Why was the world created with ten utterances? Couldn't Hashem have created it with one (Avot 5:1)? Our world is not an expression of the divine ability to act in a single moment, but to act in stages. The Ramchal – Rabbi Moshe Chaim Luzzato - wrote that each day the world gets closer to its perfection. All the worlds that were created previously were made piecemeal, but they all could be exalted. Our world was not created with the full power of the Master of the Universe. Hashem limited His power and revealed Himself in the way in which humans work: little by little, according to a divine plan which continues to be actualized over time. It is not true that the Master of the Universe needed to bring plague after plague because of the stubbornness of Pharaoh's heart. On the contrary, the Blessed One caused the stubbornness of Pharoah's heart in order to bring the plagues upon him. "For I have made his heart and the heart of his servants heavy so that I can put My signs in his midst, and so that you may relate in the ears of your son and your grandsons" (Shemot 10:1-2). In our days as well, do not despair for the Redemption which is progressing slowly, slowly. This is not divine weakness – G-d forbid, but the greatest strength for the sake of increasing the sanctification of Hashem's Name.