I kind of disagree. As I have written before, I went to take photos of the walls myself a couple of years ago when I was in Istanbul as a tourist. The place is not remote. It's so close to all the major sights, such as Hagia Sofia, Blue Mosque, Topkapi palace etc. Most of Istanbul is known to be safe and those walls are in the most touristy part of the city.
In my case anyway (I'm in my 30's, well-travelled, used to living in a large city) it didn't even cross my mind that the city of Istanbul would let the ruins of the ancient city wall, a historical attraction in itself, in the middle of that historical peninsula, to be inhabited by drug users and other criminals. I have never been to any city (excluding the so called third word, which Turkey is not) where that would've been the case.
Well, now I know that's the case. Glad they're installing security cameras at least.