I very much agree, they clearly do so in an attempt to showcase the zoo as family-owned. I guess I could have made it clearer in my original post, but that behaviour is partially why I say it operates more similarly to a 'regional/roadside' zoo than a 'destination' zoo. At a certain point, one at which Australia Zoo has outgrown, the popularity of a facility, and the amount of 'callbacks' it holds, makes these things seem tacky and disrespectful rather than respectful and wholesome.
I think Wildlife HQ has many great examples as to how to properly honor those who have aided/constructed the zoo as well, without it being tacky or disrespectful. I'll always bring up the prime example of it's Reptile Barn, in which they just have a nice wall dedicating it to Bob Irwin as a result of the great work he has done for native reptiles. To be fair, that is for a smaller budget facility, and if it were to be larger or more 'expensive', some people would likely end up seeing that as more of an oversight/waste of space than a respectful homage, but I'd view those people as incorrect nonetheless.
To directly compare that to Australia Zoo, their reptile building is now called "Robert's Reptile House", which is directly next to "Grace's Bird Garden", of which is just a short walk from "Bindi's Island", that you get to by walking a bit further past the (now unoperational) "Bindi's Pony Trails", which in itself is found by taking a right at the statue of the Irwin family after entering the zoo you've found by following the 5+ road signs of Steve Irwin, going past 2 alligator enclosures adorned with further signs of Steve Irwin, past "Crikey Cafe", the wall designated for that one time Bindi Irwin was on Dancing with the Stars, that one time Robert Irwin was on a talk show, the 'Crocodile Hunter's Story' wall, the multiple walls with newspaper clippings about the Irwins, the 'Robert Irwin Photography' store, the multiple retail stores with more Irwin-decorated merchandising than you could ever imagine... I don't think I need to go on further.