Well consider this: In the Book of Mormon, 2Nephi 2:22-23, If Adam did no sin, He would have been stuck in the Garden of Eden forever, having no joy and doing no good, because no sin was done. Therefore, Nephi is saying that to have joy and to do good, one must sin. Thus Sin is Good.
How is it that the Creator didn't know what He was doing, and needed Adam to sin?
God knows the end from the beginning. He knew way before he ever placed Adam and Eve into the Garden of Eden that they would choose to partake of the fruit of the tree of knowledge of good and evil. He knew Adam and Eve would fall and become mortal. For this reason God chose a Savior to atone for the sins of mankind before the foundation of this earth.
1 Peter 1:18-20
18 Forasmuch as ye know that ye were not redeemed with corruptible things, as silver and gold, from your vain conversation received by tradition from your fathers;
19 But with the precious blood of Christ, as of a lamb without blemish and without spot:
20 Who verily was foreordained before the foundation of the world, but was manifest in these last times for you,
If God never wanted Adam and Eve to fall, why would he place a character like Satan on the earth to tempt Adam and Eve? Why would he place the tree of knowledge of good and evil in the garden and give a commandment that he knew full well in advance that Adam and Eve would break? Why would he call a Savior before the foundation of the earth to atone for sin? Certainly if god never wanted the fall to occur he could have kept Satan from the earth, never placed the tree of knowledge of good and evil in the garden, and made sure there was no opportunity for mankind to transgress by not giving a commandment to not eat of the tree. But God did go ahead and make sure that Satan and his minions were on the earth to tempt Adam and Eve, He made sure to place the tree in the garden and gave specific command not to eat of it, and knowing full well what outcome would be, He called a Savior way before He ever placed Adam and Eve in the garden to atone for their transgression. So do you really think that God never wanted Adam and Eve to fall? God gave Adam and Eve a simple command to not eat of the tree or else they would be cast out of the garden and die. Adam and Eve partook and gained a knowledge of good and evil and became mortal. A Savior was then needed. Surely this was all by design and God wanted mankind to experience mortality and gain a knowledge of good and evil in order to give them opportunity to progress and become more like God and understand good and evil and learn to become strong by overcoming temptation and learn to love and choose goodness over evil.
Genesis 3:22
22 And the Lord God said,
Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever:
The reason God goes through all of this for mankind is because God never had the power to create mankind from nothing and create him to be perfect. Man is as coeternal as God himself and has always existed. God could not create that which has always existed to be more than what its state of existence is. He has to teach such beings to choose to be better beings. If God had the power to create mankind out of nothing, then surely he could have created mankind to be perfect. But this is not the case. Mankind has always existed and God gives them opportunity to progress.
Doctrine and Covenants 93:29
29 Man was also in the beginning with God. Intelligence, or the light of truth, was not created or made, neither indeed can be.
The fall was a progression which allows mankind to experience good and evil first hand and to learn all about it. It gives man the opportunity to overcome temptation and evil of his own free will and choice. This experience is given to mankind as a temporary state of being. Eventually all mankind will resurrect and overcome death and live forever. In the eternities, we will all look back at this mortal experience as a chance to learn good and evil and use our free will to choose good over evil. In this way we can become more like God. Nobody makes God be a good being. He does so of his own free will and choice. He prizes the good over the evil and wants us all to become more like him and be more exalted as a good being by learning to overcome evil and choose to be good beings. The fall was a necessary step in this progression. God had to give an opposing commandment to be justified in bringing about the fall. Without the commandment and its accompanying penalty, no fall would have occurred and mans opportunity to gain knowledge of good and evil and chance to learn to overcome the evil of his own free will would not have come about. The only purpose of the command was to give man a reason to be placed into a fallen situation in order to experience and learn to be a better being of his own free will and choice.