Simple... go visit the north side of the bridge, and picture what 2km of elevated pathway could do for cycling convenience.why does it need to be raised like that?
Right now you come along the bridge, have to descend the stairs at Milsons Pt, weave your way through a busy narrow street to a roundabout, turn up a one way street travelling the wrong way - yes it's marked cycleway - then pick through a few busy and dodgy sections before reaching clear road again.
Not something for anyone but an avid cyclist, I'd say...
By the sounds of this, the pathway allow you to keep your elevation instead of walking down stairs only to climb back up as high as you were, and it misses some pretty unpleasant roads too.
Winner.