Ideally, the glide path will be lined up exactly with the runway so the pilots can land safely at the end of a long delayed flight.Furthermore, raising the glide path by the recommended 1,100' and moving it 0.75 miles away will reduce the volume by over 60%.
Jet aircraft are slippery and take some stopping. A steep descent means they will generate more aerodynamic noise creating turbulence to waste the excess kinetic and potential energy. A shallow descent will require continuous engine power. Maybe you can find out what the minimum noise glide slope angle is for the noisy aircraft that land most often.