The President is given more powers when a state of emergency is declared as described in this article by USA Today.
President Obama has extended Bush's Proclamation 7463 for the 16th consecutive year, giving him broad powers over the organization of the military for at least another year.
Among them: the ability to call up the national guard and deploy those troops overseas. As of last week, 16,345 guardsmen remain called up under the legal authority involved by that proclamation, the Pentagon said.
The emergency also gives the president — and his successor — the authority to "suspend the operation of any provision of law relating to the promotion, involuntary retirement, or separation of commissioned officers" of the armed forces. And he can appoint an unlimited number of new one- or two-star generals, waiving promotion requirements and legal limits on the number of officers.
Also, the reason for the extension:
As of Sept. 30, about 25,700 guard and reserve troops remain involuntarily called up to federal service on the authority of Bush's proclamation, the Pentagon says. Canceling the state of emergency would allow them to go home.
Eight generals and admirals have been appointed to their positions despite laws limiting the number of general officers in each service. That's because the state of emergency allows the president to bypass the law and appoint an unlimited number of one- and two-star generals.
[...]
The Department of Defense is conducting a review of how it would meet staffing needs if the president fails to renew the state of emergency, said Navy Lt. Cmdr. Nate Christensen, a Pentagon spokesman. That review has been going on quietly for years, and the emergency has been extended each time.
So, the state of emergency is extended so that a number of officials appointed in excess of normal limits, especially those stationed in the Middle East, can continue to hold their positions.