It's just a bandaid for the impact of the dugongs, now that Singapur wants to emulate EK with a 380 only ops into LHR.
These things slow down airport operations. The separations are lowering the hourly movements, especially in a mixed use with narrow bodies. No one admits, but simply do the maths.
Then pretending that a steeper approach path for dugongs reduces noise omits the fact that they have a way shallower climb out path than twins (the overwhelming number of movements) and that means more noise impact!
Unless you only want to land during the mentioned hours.
Airports are limited by landing slots, then by t/o slots. The situation on the tarmac follows third. So the dugongs are hampering airport efficiency. That's the real impetus for TC to come up with these silly proposals.
If you want to introduce some (slightly less safe) stunt procedures to increase capacity, it should therefore not be tried with the least flexible aircraft, but maybe with the more flexible ones, to begin with.