I had to read your mini rant about Melbourne Zoo several times as I was a tad surprised at your seemingly vehement disgust at what has occurred at the zoo during the past decade. My one and only visit to the zoo was in 2007 and I was duly impressed. However, that was obviously before the lemur walk-through area (which doesn't look that bad at all), Wild Sea, Growing Wild, Lion Gorge and the baboon exhibit (perhaps most impressive of all). What do you think of the new baboon accommodation? When I was there those primates were shunted to the side in an awful chain-link cage that brought back memories of an earlier zoological epoch.
From photos the brand-new, $5.6 million Lion Gorge complex does appear a bit "boring" but the use of large viewing windows is surely an excellent addition to that enclosure. Wild Sea does come across as a bizarre concept as the cement outcroppings in the seal pool are not textured or naturalistic whatsoever. What is up next for one of the world's oldest zoos? Snow leopards and Syrian brown bears receiving updated exhibits?
My objections are more to the totality of developments over the past decade or so than to any one exhibit. The lemur walk-through isn't bad per se, and I think my initial reaction upon seeing it for the first time with Chlidonias was fairly positive. But it's still just a few lemurs sitting on the ground, in front of a concrete wall. They only seem to use a small portion of the exhibit, at least while visitors are around. Unused space in an exhibit is a sign of failure to me. The ruffed lemur enclosure next to it is much worse. You look down on the lemurs from above, and they don't really have much incentive to climb so they have been curled up on the ground every time I've seen them since they moved. And that ground is, bizarrely, partly covered by black pebbles.
I realise I did neglect to mention the large glass viewing windows into the lion exhibit (I was thinking of the hunting dog enclosure when I wrote it, as well as the failure to even attempt to screen any of the big black fence behind the lions). But the main viewing window is inside an echoey building (another unnecessary building!) that also has a view into the (as yet unoccupied) croc enclosure and a couple of small terraria (which seem to be the zoo's way of justifying all these pointless rooms). The damn thing has a single glass door that creates a traffic jam in and out. There's just been no thought to amenity at all.
I'm wondering what happens to ideas at Melbourne. Growing Wild was supposed to have a stage II. What happened to it? Early signage indicated strongly that P̶r̶e̶d̶a̶t̶o̶r̶-̶P̶r̶e̶y̶ ̶P̶r̶e̶d̶a̶t̶o̶r̶s̶ ̶Lion Gorge was going to be a rotation exhibit. That's clearly not happening.
I also despise the noise pollution that has appeared in the zoo. There are two particularly annoying examples I can think of. I've complained before about the audio-visual display in Wild Sea (that has animated whales and dolphins etc), and the piped in whale sounds on the main drive outside the complex. There's also a thing set up near the gorillas that is meant to encourage people to recycle phones for their coltan. A worthy message, but it didn't need to be done with a constant stream of piped in ringing sounds. The gorilla forest used to be the only immersive complex in the zoo but not anymore.
As Tetrapod said, the Melbourne Zoo of my childhood was simpler but it had more exhibits and, importantly, far more vegetation. It was softer, visually, than it is now. There are cheap (and some expensive!) and ugly buildings all over the place. It seems the current director can't bear the thought of visitors not having an education building, function room or shop in their direct line of sight. And that's before you get to the frankly ugly exhibits all over the place or the sheer amount of walking between exhibits. I overheard one guy complaining that he'd been at the zoo for half an hour and hadn't seen an animal, and it's a fair criticism. One of Melbourne's assets is its large open spaces not taken up by exhibits (something Adelaide and Taronga don't have), but when you've rationalised the collection down massively you're left with long gaps between exhibits.
If you look past the flashy price tags, you'd hate the new Melbourne Snowleopard.