I got to this thread late. My first thoughts expand on james_woods mention of "free will" and tec's mention of "knowing the difference between good and evil". Eating the forbidden fruit is the first mention of humans exercising free will ,right? And the difference between "knowing good and bad" could mean understanding the consequences of good and bad actions? Or it could mean losing your innocence and naivety?
Isn't that the price that most people pay for "learning the hard way"? The consequences of poor decisions catch up to you, and at the same time you destroy once-in-a-lifetime opportunities. (innocence, health, familial relationships, criminal record, etc.) Knowledge and understanding gained from bad decisions and experiences often exacts a price on your health, future success, or standing in society (symbolized by the tree of life?), all of which were ruined in Adam & Eve's circumstances.