From what I heard the mappin terraces had serious infrastructure problems and due to it being a listed area they couldn't change anything. I think that I read this at one of the early photos of the outback exhibit at the london zoo gallery.
And to throw my own hot take, I think that insect/butterflies houses are a waste of space. I would much prefer that space to be dedicated to amphibians/reptiles/birds/mammals. I've never seen the appeal for this type of areas and normally skip the exhibit unless there's a unique species in there.
Yes, infrastructure issues are why the Aquarium was closed, although seeing as the current wallaby and emu enclosure is in front of the terraces rather than on them, the state of said infrastructure wouldn’t be affected by the inhabitants of that paddock. It is worth noting that it being a listed building only prevents radical reform or complete demolition, they would still be able to make the repairs needed to the actual structure. The issue is expense.
I don’t take issue with the fact that you don’t enjoy insect houses (each to their own), but calling them a waste of space is just untrue (I get this is hot takes) - when you look at the sheer number of seriously endangered invertebrate species kept, bred, and sometimes eve released in zoos, such as Lord Howe’s Island Stick Insect or any Partula Snail, it becomes immediately obvious that the holding of invertebrate species in zoos is crucial. The educational value is huge for species that are so widely engulfed in irrational phobias, and for some species such as butterflies there is an enormous amount of joy to be found in admiring their variety of colours and beauty.
As we are already on the subject of London Zoo, it feels fitting to mention their invertebrate house, one of the very finest in the world, which after several name changes has now been dubbed ‘Tiny Giants.’ Partulas are bred here, but it is also a thoroughly enjoyable visitor experience because they avoid the easy trap of laying out the exhibit as row after row of identical boxes. Instead, you can watch diving beetles through a magnifying glass, or observe ants with no barrier, or even step into a walkthrough with spiders, with a small coral reef to top it off. I’m not really interested in invertebrates either, but even I find much joy in this exhibit. It leads me onto a ‘hot take’ of my own (although I suspect many members here share it) - that any animal, or any exhibit ‘genre’ can be made interesting if the display is made engaging, rather than repetitive.