So, we are told in scripture that everything redounds (returns) to God's glory. One of the meanings of the word "glory" in Hebrew is to imply immensity, heaviness, volume, impressive . . . along with splendor, magnificence, radiance. . . .
If the purpose of creation--especially this creation including the resultant fallen world and creatures--is ultimately meant to all redound to the glory of God, I am not surprised to see it is precisely . . . the way it is.
Would a perfect world, with perfect creatures who did nothing but love and worship God forever exemplify the immense and magnificent characteristics of God? Yes, and I would suggest that such would show more of His "glory" than if He were simply existing alone, by Himself.
BUT would it not reveal MORE of His glory (immensity, impressiveness) . . . to create a world that was capable of rejecting Him, falling into corruption and chaos thereby, where He then condescends to become as one of the creatures in that fallen world . . . to defeat the corruption . . . save it and THEN return it as a perfect world with perfect creatures (rescued from "darkness") who love and worship and appreciate God's glory all the MORE . . . than if they had never fallen away in the first place?
Let's say you were born into beauty, perfect health, splendor, power and wealth, surrounded by similar people who all have the same. From your first conscious moments it was all you knew. It was the air you breathed, "the water in which you swam." You knew nothing else--indeed couldn't even conceive of anything else (poverty, lack, hunger, disease, ugliness etc.) because you had never seen or experienced it.
Someone comes to you and says, "There is a wondrous fountain, miles away, which gives health, wealth, beauty and well being. All you need do is drink from it and these things will be yours! But first, you must travel through a desert . . . then a malarial jungle with wild and poisonous monsters . . . and through lands of thieves and murderers. . . . You will starve, be beaten and persecuted, robbed, and will travel alone. BUT, at the end, there is the fountain which will make it all worth while!"
Why would you bother? You already have all the things the fountain offers. In fact, you don't really even understand the offer, because these things are all you've ever known. You don't even know that they are especially desirable compared to the lack thereof. Starvation? A beating? Poverty and loneliness? What even are these things? You have what you have, you are what you are, and that is all there is, taken for granted.
Does not creating a relative reality . . . a creation which is capable of existing with a relative lack of God--of His love, power, abundance etc. on display--where His rejection (by that creation) leads to death, misery, poverty, disease, horror, depression, murder, infidelity, war, perversion . . . create a situation where His glory (immensity, capability) is revealed ALL THE MORE by the contrast?
And would not a creature who had gone through an experience where God was NOT the center of all things then love and worship and appreciate Him so much more meaningfully because of having experienced what "life" was like without Him? Contrast and comparison between things brings a deeper, richer, more pleasurable enjoyment of the better thing between the two. Especially the more those two things are different.
Imagine God created a world which was just a little bit different than Heaven. No pain, no sadness, no conflicts . . . but everybody walked with a limp, that's all. Oh, a tiny bit of discomfort in that limp, but otherwise everything else was perfect and the people lived forever. Yes, those folks would probably enjoy somewhat better going to Heaven where there was no limp and would praise God for the upgrade . . . but compare it to a people who practically went through a living hell, threatened with death the whole time--in a world run by sadistic and psychopathic invisible entities--who THEN got to live in Heaven thereafter forever, never to suffer again?
Now, you might say, "but really? Must the world be this bad and life so hard . . . to show such a contrast? Couldn't it have been designed differently, better than this, in order to reveal and share God's glory, if that is the purpose?"
And I would just say, "Presuming (thus believing) God's Word is The Truth; and that He is perfect, holy, good, omniscient, omnipotent, lacking nothing, needing nothing, full of grace and mercy, Who is love . . . then why would I question whether He could have done it a better way . . . according to my limited, fallen, corrupt, sinful, self-serving mindset and heart? Who will I be siding with: finite, naturally God-hating men in rebellion against God--"children of the devil"--though they be fancied as scientists, atheists, agnostics, philosophers, artists or whatever . . . OR . . . do I suppose that God, Who is all wise, all powerful, perfect, righteous, eternal . . . that HE made this world, with His plan and purposes in just the way He intended it and that it is undoubtedly the best way for His purposes?
Now, one might argue, "but you are presupposing there is God in the first place to bring forth your answer and analysis. But note this: to even question why there is "evil" in the world itself presupposes that there is a God! If there is no ultimate Authority--no objective Truth, no "Lawgiver", no objective "right" and "wrong" . . . then there is no such thing as "evil." There is no objective, transcendent meaning. It is only because there IS a God--an Authority above and beyond creation--that "evil" can be perceived or said to exist.
[Ahh . . . but gotta go to church right now, so will continue asap, God blesses you.]