Why Did God Put the Tree of Knowledge in the Garden to Begin With?

  "If God knew the humans were going to eat from it, why did He put the Tree of the Knowledge of Good and Evil in the garden to begin with? Why not just keep it far away and out of their reach?"
This is a perfectly fair and legitimate question which people ask about the Genesis account, because if God is in fact omnipotent, then it was perfectly possible for Him to either remove it, or not have it grow where he was going to put our ancestors in the first place. So why was it there? Why put something so potentially dangerous to our species within arms reach knowing that they would eventually eat from it? A common answer is that it was a part of God's larger plan for human beings. But then this also has the consequence that God Himself had agency for, and is ultimately responsible for, the fall of Adam, something which is, quite frankly, absurd. And, more directly, it assumes that God has an overarching plan at all.
God exists, and time and space are dimensional vectors which move through Him, not vice-versa. He knows what has happened, what is happening, and what is going to happen from our perspective, because He is already, constantly present in the happening. Nothing happens without His knowledge because nothing in time or space does not pass through Him when it does. There is nothing, no particle of matter or energy with which He is not already intimately in contact because they are ultimately formed from His own Being, being the source of all energy in existence. So of course He knows what will happen and every possibility of what can happen.
But knowing what will happen or is already happening is very different from exercising agency in the happening. Knowing what will happen or what is happening is very different from planning it to happen. And assuming that everything which happens is a part of some overarching plan of God's removes all responsibility and agency from the sentient beings, the human beings, who made the choices which initiated the happening. Knowing that they are going to make those choices is very different than planning for or causing them to make those choices. Just because God knew they were going to eat from the Tree doesn't mean God planned for them to do so. It wasn't God's choice for them to totally ignore His warning about it and do it anyway.
As I have written before, God respects our individual free will more than we do, and actually interfering with that free will, directly "reprogramming" on the fly against that person's volition, so to speak, is anathema to Him. It's not something He will do. Our choices are what define us and make us the individuals we are, and whether those choices were from before this Fall or after it, they are still ours to make for either benefit or harm. When He created us, one way or the other, He didn't set out to direct our lives like a puppet master. He created us and then let us do what we were going to do, acting, speaking, and responding as we were going to without any direct puppeteering from Him. These actions of ours, these words, these responses set the ball in motion for all of human history entirely without plan or direction on His part, though not without His interjection at times.
While the overarching direction of human history was left to our choices and responses as individuals, God did act in response to mitigate the damage and teach us how to work around and deal with the damage and consequences of our choices. He did act to provide for us a solution to our behavioral malfunction brought on by our poor choice in the garden. This is the plan which God had from eternity, not to direct each and every one of our lives like a puppet master, but to give us the tools to bypass our inherited malfunction so that it didn't have to impact everything we did or said, but still keeping it as our choice whether or not to make use of it.
As for why God left the Tree of the Knowledge of Good and Evil in the garden? I suspect it was because it was a primary food source for a particular animal that lived in the area. Rather than change everything, it made more sense and would cause less disruption to just give the new residents a warning not to eat from it. Yeah, He knew they would eventually not listen, but they didn't know that, and they did listen for a long time until someone chose not to. But even that choice, fraught with disastrous consequences as it was, was honored by God as their choice and one He wouldn't take from them.
Just because God "can" do something, doesn't mean He will. Just because He has, by His very nature, the ability to rewrite the fabric of reality on impulse, doesn't mean that's something He would do if, for no other reason, than it would mean the loss of every unique person and individual involved as they are rewritten. Think of it like a saved game on Skyrim or another RPG. You spend hours and hours working on a character, leveling him up, buying or building a house, getting him married, getting him kids, and investing in his life. And then you decide to start a new game and overwrite the save file. Everything that character was is lost. Now imagine if it was an AI character doing it all on his own, making his own choices, fighting his own battles. Sure, it's your game. You could start a new character and overwrite the old one, but everything he was would be lost. He would have no say in the matter. Wouldn't that be almost tantamount to murder? Maybe even worse, because at least with murder, the consciousness or soul survives even if the body doesn't, but here, not even the intelligence or "consciousness" would survive the overwrite. There are things God can do, but won't do because He loves, and because He cares about each one of His creations individually. He would rather that individual make his own choices, even the harmful ones, and be who he is than overwrite him and wipe him from existence by taking his own free volition from him.
So, yes, He knew about what would happen. No, it wasn't a part of His plan because there wasn't an overarching plan to begin with. There was just a bunch of human beings in a garden paradise who were left to be who they were going to be. No more, and no less.