Government agencies already can and do track network activities and tie them to IP addresses. Bitcoin, and blockchain.info in this case simply makes things fair by making certain - easily available - information public, instead of being exclusively available to chosen entities. That is a good thing. Collect the IPs. You might be surprised what you find in there. What you cannot find leads us to the next point - and is also what others cannot find. Again, very fair.
As already pointed out, what is available are the transactions my node has
relayed to the blockchain.info server. It is hard to prove that I was the one who created the transaction, and I can make this even harder by connecting to Tor, too.
OP, does any of this make you feel any better?
What if goverment allow bitcoin but ask all bitcoin client register IP when they get a broadcast for certain period?
Again, they don't need to "ask" you to this. This is readily available to them if they want to have it. Again, Bitcoin removes at least some of the unfair advantage of government over people by making the information available
to everyone.
