Tonus -I doubt that the intent was to promote the idea that ignorance is bliss, but it's an unavoidable conclusion. Or that god's perfect setup was undone by allowing humans to make their own decisions.
As a person of faith, I believe it's simply so that I may understand what happened, why things went south for mankind. The snake was clearly at fault in my opinion.
It also brings up the question of how desireable free will is. If there is one path that makes us happy and prosperous, and every other path leads to misery and suffering, what good does it do us to have a choice?
I agree that free will only goes so far. In the end, one is still subject to God's 'laws'. Saying I choose to not subject myself to God only to suffer hell or non-existence is really not much of a choice.
The question is about humility. Will I recognize God as my creator and I am the creation, only human? That he is subsequently my eternal superior? Or will I refuse to accept that there is no other way and go down into non-existence.
The snake apparently refused. And very likely lied to Adam and Eve simply out of spite.