In places that have a history of subverting democracy by voting in dictatorial leaders all on their own having an institution that is supposed to over throw them strengthens the democracy so long as it's functioning properly and only comes into play at the right times.

It's easy to want a dictator when you're in the majority, they hold the beliefs you do and you're probably going to not be the groups oppressed (at first). Raw complete democracy doesn't have a good way of dealing with a majority wanting to repress a minority. So founders (at least smart ones) put checks in to balance that, in the US it takes the form of the Supreme Court and in Turkey they have the military as a final ultimate check.

edit: Source for my original post (can't edit now) of the history of Turkish coups: http://www.aljazeera.com/news/europe/2012/04/201244728146879...