First of all, bitcoin is pseudonymous, not anonymous. This means that you don't know exactly who the other person is, but you have someway to identify them.
Secondly, blockchain.info does not give you the ip address of the person. It only gives you the ip address of the node that relayed the transaction to them, which is most likely not the person that sent the transaction. It is very difficult, next to impossible, to determine the ip address of the node that created the transaction.
Thirdly, you should not be reusing bitcoin addresses. By keeping your addresses separate for each transaction, then whoever is sending you Bitcoin will only know that you have at least the amount they sent you. They don't know how much you actually have. Services who also use new addresses for every transaction also protect your anonymity since others won't know who owns that new address. It could be your own wallet, your friend's, or that porn site you pay for.
There are also some services that can help you anonymize like mixers or CoinJoin transactions.
But everything seems baseless when it comes to converting your Bitcoin into fiat using an exchange that has almost all your information and is connected to bank. Governments while making Bitcoin legal are now regulating exchanges and thus can have hold of these information when needed. Also there is a risk of hacking. Until Bitcoin stays on internet, there are various ways of keeping it anonymous. But when it is converted to fiat. There is an identity threat.
Exactly. The fines for not performing proper AML/KYC on a customer transferring over 10k value in x time frame are steep, and the ultimate risk on an aggregious enough violation would cost the exchange the ability to operate period. Ask BTCE and the myriad, pissed off BTCE users on the board (the furor on that one died pretty quick, no?
). It is the governments job to ensure there is no malfeasance associated with its currency, unless it is getting a cut of the action (ask Ollie North about that one). If you want to skirt the rules, dont buy anything that is highly government regulated. That would include fiat (you are buying fiat when you exchange btc for USD) and specie (precious metals).
its hard enough with the regulations that concern fiat, without even involving bitcoin. they will report a 2K transaction if they deem it 'suspect', this has happened to me personally, many, many times.