And what is it that you want to do when you find the BTC? Beat the private keys out of anyone that has even a satoshi of them in their wallets? Who's can say those BTC have long been used/traded for good or services? Or even if they ended up in a cold storage wallet long ago?
I think you really need to think about what your suggesting; a witch-hunt plain and simple.
What I'm suggesting is 100% sound
Let's examine your excuses individually:
1) "And what is it that you want to do when you find the BTC?"
A) return it to it's rightful owner, that's what you are supposed to do with stolen money. Sure that's not news to you?
2) "Beat the private keys out of anyone that has even a satoshi of them in their wallets?"
A) I try not to operate like that any more
3) "Who's can say those BTC have long been used/traded for good or services?"
A) Oh, goodie, they were spent for "good or service", so now you have names, faces, addresses, email addresses, phone numbers, cities, countries ... to add to all of the other electronic connections. At that point anonymous becomes a less anonymous.
4) "Or even if they ended up in a cold storage wallet long ago?"
A) cold storage doesn't represent a dead end it represents a good idea of where it is, who has it and that it is still available.
Even if someone attempted to wash the dirty money it will show on the block chain.
The whole cryptocurrency economy suffers when irresponsible behavior is rewarded with a blind eye.