Satoshi was simply a genius. By creating a pseudonymous coin, he/they created a coin in a friendly way in regards with the authorities - a coin that would not instantly become a state's enemy.
It did work out well, but I don't think it's a primary consideration. According to the white paper:
We need a way for the payee to know that the previous owners did not sign any earlier transactions. For our purposes, the earliest transaction is the one that counts, so we don't care about later attempts to double-spend. The only way to confirm the absence of a transaction is to be aware of all transactions. In the mint based model, the mint was aware of all transactions and decided which arrived first. To accomplish this without a trusted party, transactions must be publicly announced, and we need a system for participants to agree on a single history of theorder in which they were received. The payee needs proof that at the time of each transaction, the majority of nodes agreed it was the first received.
If we want to be completely specific,
this is the reason why Bitcoin isn't anonymous.
