We must have suffering and death because we chose it. It's that simple.
The pat return to that is: "I didn't choose it? Why should God punish me for Adam and Eve's sin?"
Dwell on it for a minute. Hindsight is 20-20. To the observer, satan's temptation may seem trite. But one must take Adam or Eve's place - walk around in their skin, so to speak. These people were created in the perfection of their nature. They were graced with God's Image and Likeness, Sanctifying Grace, and some extra gifts besides, including complete control over their bodies and desires. In that way, and perhaps even physically, somehow, they walked with God in the Garden. They had seen these goods and were in awe of them. They would not abandon them so lightly.
But the devil most often tempts us with goods. He did the same with Adam and Eve. Truly, the knowledge of good and evil would make them more like God. Yet, the means to achieve it would require disobedience to God's one command. So the devil attacked Adam and Eve's Faith, saying they themselves would become gods; he attacked their Hope, leading them to doubt God's ability to care for them; and he attacked their Love of God, placing their own desires above their obedience to God. And they chose to believe him, rather than God.
And this applies to us because we are all of the same nature. We are all being given chances to prove ourselves. Why complain that we are also being tested? Now is the time to prove that the devil will not conquer us. And by the happy fault of Adam and Eve, and the Passion of Christ, we are being given a much greater reward for our struggles.
God love you all,