Metal detectors and x-rays at hotels in Istanbul has in my experience always been a mainly decorative feature. I have always wondered if it is a regulatory requirement, or something that the international hotel chains require. For the hotels in Istanbul I have stayed at where they actually monitor them, it has always been more pretending than actual doing anything. That being said, I have never felt there was any great reason to have these installed at hotels in Istanbul, so I have always just been mildly amused by the fact that they were there but so blatantly ignored. To some extend it is the same in Moscow.