andrewr.
From memory, a 3 degree path requires a descent from 3000ft just passed AKDEL (~0.3nm). So AKDEL is about in the position to be on profile at 3 degrees. Typical turn radius for a 90 degree turn is about 2nm at that point (note 185kt speed restriction). This means that aircraft will not be established on the final approach path (ie complete the turn) until after the profile descent point. For an RNAV approach this is OK. For a precision approach this is not.
Precision approaches require establishment on the localiser before intercepting glide path. The GLS design required getting the aircraft under the glide path, and making the turn lower so they could establish on loc and intercept glide path from below. Doing all of this at 3000ft (particularly on a hot day) would have caused problems, and is not inline with ICAO procedure design rules (PANS-OPS).
Alpha