Are you aware that 10% of the bitcoins in circulation are currently stolen? Are we going to do anything about it?
Are you including bitcoins that were willingly given to the thief or situations where large quantities of bitcoins weren't stored in cold storage at all (such as inputs.io, MtGox, pirateat40, SilkRoad, etc) in your calculation of "10%"?
If so, please explain how your proposal would have helped in any of those situations?
If not, then please explain where you come up with a number like 10%?