Satoshi is part of the design of Bitcoin. It is probably a pseudonym for a decentralised group of people. That way, they remain anonymous. Even the anonymity of the creator could look like a bad thing, it has more advantages than drawbacks. That way, nobody can attack the "head of the project" to discredit it. Look what happened with wikileaks. They attacked Assange to mess with everything.

So, Bitcoin is descentralised and under pseudonym to protect it and its creator too.