Going through the mailing lists, there is some discussion about how bitcoin should be considered like "grains of sand" or a "bucket of water" transferred around from wallet to wallet. However, this mechanism of keeping a the whole ledger of who owns what all the way to epoch, would not scale.
I haven't found a deeper discussion thread on pros and cons of having the coins (all the way to Satoshis) to be tagged , so that a database of who is a particular owner of a particular coin can be kept.
If there is such a thread, would be great , if someone could link.