It might be a "quick" transit thru KL - but it's about 4am body clock ! Why not fly SQ if you're wanting to fly to Istanbul 

Qantas's billboard on the approach to Melbourne airport flogging these flights is hard to miss - but still leaves the unanswered question for a Victorian of just - why ? What's the point of using a domestic 737 for your trans Australian legs when there are such nicer options like SQ or a middle E...

"Significantly, the Project Sunrise A350 jets have just over 40% of their space assigned to premium cabins".  I suggest you pull out a tape measure. Just above this statement was a map of the plane which clearly showed at least 60% of the space of the plan is premium ! Maybe you mean seats ?

In which case let's allow Turkish to also have unlimited Melbourne Sydney too ? Why stop there. How about Istanbul - Sydney - Haneda, and Istanbul - Sydney - LAX while they're at it. Would tick all same boxes. 

So unclear as to why Turkish feel they'd be 'entitled' to have 5th freedom rights between AU and SG. A most valuable route - what's in it for Australia in terms of Turkish getting a piece of the action ?