Western plains hasn't had any majour redevelopments or developments in a long time. All there stuff has been either conservation based and mostly of display. Or in the realm or cafes, play areas and accomodation. Which given the location is more genuinely needed then say what taronga has done. The zoo is in desperate need to of revitalising itself, they have lost a large amount of species and haven't gained anything substantial apart from the platypus HQ.
It's high time the zoo redesigns itself and starts redoing itself or it will suffer more visitor losses. As soon the other open range zoos will be miles ahead. Why they have never redeveloped the primate areas and added new exhibits for gibbons (the simian exhibit was actually quite small and the reason I believe they didn't require them), and add in exhibits for chimps, gorillas and squirrel monkeys is beyond me. The primates were popular and they have let them dwindle down. A lot of space that used to be used for ungulates is now being used for ungulates but on repeat. You see zebra on the savannah, you see zebra in there species only exhibit. The taronga foundation needs to start realising if they dont start putting effort into the zoo they won't get increased visitation its too far in the middle of no where to be so average.
While I enjoyed the Wild Asia section of the zoo, I did notice that there were a few areas where it seemed like there were a lot of walking for not many animals. Perhaps it's more noticeable because the rest of the zoo is drive-through. It would be interesting to see how they redevelop it without losing too much of the tree cover, which is an asset.
I thought that the siamang (now white-handed gibbon) exhibit was more than adequate. They have access to two islands, so it would be comparable to the exhibits at Mogo, I think. While repeat exhibits may not be as engaging for visitors, they do assist zoos with holding the animals they breed long-term.