In the midst of Exodus 9:14 – 16 there is purpose given that is stunning:
“…in order to show you My power and in order to proclaim My name through all the earth.”
One purpose of the plagues, the seals, the trumpets, and the bowls is to reveal God. It is to draw people to Him, to demonstrate His power and nature.
Man is stubborn. Committed to disobedience. In Genesis 7, God wiped out the world and started over. He promises in Genesis 8:21 He will never do that again until He creates the new heaven and the new earth, 2 Peter 3:10 – 16.
In the meantime, when He sends difficulty, the purpose is to demonstrate to us, this stubborn people, that it is He who is in control. It is, as Peter tells us in 2 Peter 3:15, a call to us to accept His grace. To acknowledge our rebellion and come to Him and have our relationship restored.