Re: God's purpose in memory
Well, God did create all things perfect. I do believe that Adam and Eve had total recall before the Fall (otherwise they could have used that excuse too!) I believe forgetfulness is truly an effect of the Fall yet there are a few remnants of people that have a 'degree' of total recall. (oxymoron alert). We judge it a pity when a person can't remember names and dates very well indicating a loss of perfection.
As such I am not so sure memory as we know it is designed. Memory only becomes an issue when there is forgetfulness. If there wasn't such a thing as forgetfulness we wouldn't be having this conversation. 'Not-forgetting' is just part of God's nature which He breathed into Adam at creation.
Now as fallen creatures 'forgetting' serves the purpose of our continual dependence on God where we find ourselves 'taking closer heed to those things we have heard lest we let them slip'.
♪ Each day may Christ become clearer, His Cross dearer, Our Hope nearer. ♫