To do that, you will need everyone to use only one address for all their coins and nobody is doing that. Why would I put all my coins in one big bag and advertise to the world that I am filthy rich? It would be stupid, because you would be painting a target on your back for hackers and thieves to hunt you down.

Let's say somewhere in the future, some steroid induced super computer, finds a way to encrypt private keys, which addresses would you think, will they be going for? Developers will strengthen the encryption if this happens, but by that time all the big addresses with the mother load will have been targeted. ^grrrrrrr^