The Fall is the beginning of morality without it Adam and Eve would be forever innocent and unable to reproduce like God Commanded.  
 
The fall gave us knowledge of Good and Evil the consequences of this are two fold we became mortal (physical death) and had to be separated from God (spiritual death). 
 
The irony is that the Scriptures show this as a neutral or positive event but false teachings paint it as terrible.  
 
If God was so angered at Adam and Eve why did he make them cloths and instruct them how to survive in the world outside the Garden? 
 
Seems like God wasn't angry with Adam or Eve for there decision at all to me. In fact the only thing punished is the serpent who loses his ability to walk and now has to slither on it belly.  
 
Now the next question is why did man need to be separated form God? 
 
We believe this life is a test of our faith and devotion to our Heavenly Father and through it we can become more like him. 
 
The only way to prove our devotion and progress to be more like him is through faith meaning that a Fall was necessary for out eternal progression from pre-mortal existence (before the creation of the Earth) to moral existence on Earth without any knowledge or proof of our God besides our faith in him.  
 
We could not progress any further in the presence of our Father we needed to be separated but God cannot make imperfect things so man had to choose separation from God by partaking of the fruit of the Knowledge of Good and Evil.  
 
While Adam and Eve sinned by doing this they can be forgiven of this sin through the plan of salvation and Jesus Christ like we all can. There transgression is no more or less damning to their souls than our sins are to our souls.  
 
This man made idea of this terrible sin in partaking of the fruit and how all mankind is tarnished by it is not biblical no descendant is tarnishe by a parent unless they choose to follow in the parents footsteps and rebel against God also.  
 
After the fall Adam went on to be a righteous and mighty Prophet of God and taught his children the will of the God and the coming of a savior so man could return to there God's presence.  
 
He is the first prophet and the first Patriarch, the father of all mankind. We know that Adam is the Archangel Michael who lead the forces of God against Lucifer when he rebelled against God. He was such a noble and valiant soul that God trusted him to start our progression in mortality, through the deception (though the one truly deceived was Lucifer since he deceived us into being able to progression)of the serpent.