The US President is, as we all know, the "World's Most Powerful Man".
So why then can't he have free reign?
Because he's not a dictator. Rather, the president's authority is limited to that which the Constitution specifically provides.
Much is expected of Obama. I don't remember a president taking office with greater expectations than Obama has. While reagan is revered today for his presidency, I don't recall as much excitement in 1981. Of course, the hostages were released on his innaugural, so that was exciting.