Mind if I jump in?
I believe that the tree of life and the tree of knowledge were placed in the garden in order to teach Adam and Eve good from evil - I am Christian, this is not from the Bible, it is from another book that I consider scripture, and I think explains part of it well:
11 For it must needs be, that there is an opposition in all things. If not so, my first–born in the wilderness, righteousness could not be brought to pass, neither wickedness, neither holiness nor misery, neither good nor bad. Wherefore, all things must needs be a compound in one; wherefore, if it should be one body it must needs remain as dead, having no life neither death, nor corruption nor incorruption, happiness nor misery, neither sense nor insensibility.
12 Wherefore, it must needs have been created for a thing of naught; wherefore there would have been no purpose in the end of its creation. Wherefore, this thing must needs destroy the wisdom of God and his eternal purposes, and also the power, and the mercy, and the justice of God.
13 And if ye shall say there is no law, ye shall also say there is no sin. If ye shall say there is no sin, ye shall also say there is no righteousness. And if there be no righteousness there be no happiness. And if there be no righteousness nor happiness there be no punishment nor misery. And if these things are not there is no God. And if there is no God we are not, neither the earth; for there could have been no creation of things, neither to act nor to be acted upon; wherefore, all things must have vanished away.
14 And now, my sons, I speak unto you these things for your profit and learning; for there is a God, and he hath created all things, both the heavens and the earth, and all things that in them are, both things to act and things to be acted upon.
(Book of Mormon | 2 Nephi 2:11 - 14)
in short, without choices, there would be no free will. Without free will we would be unable to love, unable to do anything of ourselves. I suppose you could ask - why provide the choice between the two trees? why not just choose between harmless apples and oranges? I don't think God wanted our choices to be limited in that way though...
Like Adam and Eve, we are all free to choose - and not just blindly choose, but to make an informed decision after experiencing both sides of life.
Therefore, cheer up your hearts, and remember that ye are free to act for yourselves—to choose the way of everlasting death or the way of eternal life.
(Book of Mormon | 2 Nephi 10:23)