The President has all the power to curtail these abuses.  Unfortunately, reducing your own power is not something that comes naturally to most people.  Additionally, any reduction in the national security apparatus will be a political disaster if another terrorist attack happens, so inaction is the prudent political course.  It’s a tough problem to deal with and currently it seems a majority of Americans are more concerned with security than freedom.  Until that changes, our elected officials will likely just voice concern and persist with the status quo.