This is a classic dictatorial move. I think there may be some degree of concern about maintaining democracy, and that may even be the main goal of these measures by Erdogan. However, it certainly doesn't hurt, in Erdogan's eyes, that these measures will increase his power, while still being seen as simply increasing national security and protecting democracy.
The Turkish president has recently expanded civilian authority over the country's military. This will likely strengthen the president's power; allowing him to remain president for a longer time. Many have feared that the Turkish governments will use the attempted coup as a reason to crack down on personal freedoms and individual rights. Placing the military under further control will likely consolidate the government's power.
I'm not sure I even believe the coup was real, it would be just like the president to stage a fake coup so he could extend his power. He got rid of 2,700 judges and jailed basically anyone who ever spoke against him, all under the guise of responding to this coup. The president is power grabbing in any way he can, especially with the use of the military.
The military just attempted a coup against his government, which was a glaring view of a weakness that needed to be dealt with. Changing the military structure can only fortify his government and his control over them. It is a very prudent, powerful move that will definitely keep him in power.