The Tunisians did not take Iraq as a role model when they revolted against Ben Ali. Nor did the Egyptians. There demonstrations are as a result of decades long poverty and political oppression. The movement started from within and it reached out across the political divide.
Oh and the Americans may have implemented a democracy in Iraq, but it doesn't mean its a very good democracy. Its shabby and political dissent is still crushed. The media is censored and its a controversy to speak out against government institutions.
The Americans have come and gone but in reality very little has changed in the region. The only thing it has inspired is a culture of anti-US hatred.