Your comment is factually incorrect. After the 1967 conflict, Israel acquired all of Jerusalem. They chose to relinquish day-to-day administration to the Muslim Waqf as a sign of good faith (they had absolutely no obligation to do so) but retained security control.

The metal detectors were only installed after a Palestinians murdered police officers in cold blood. And they were installed strictly outside of the Temple Mount (in the paths leading up to it).

The fake outrage that followed was all but predictable. Metal detectors do not prevent Muslims from praying in the mosque, but it does prevent them from smuggling in knives and guns as they have done in the past. 
There is only one reason they would want them removed...