Under the emergency rule, the main motivation on the part of Erdogan is not to crack down on the media, which he has done already. He's really going after the town hall meetings and the rallies during the election campaign period. Under the emergency rule, even the local government or the district government can ban any meetings or assemblies if it sees some kind of justification based on the national security threat, which nobody will be challenging. That's why he wants to go to snap polls under the emergency powers. The opposition parties will not be able to hold election rallies or protest rallies. In many cases, they may cite a terror threat of some other excuse just to shut up the town hall meetings. That's the main purpose.
On April 19th, 2018. See this statement in context.