I personally don't think that an animal most people see everyday and know everything about can be as educationally useful as most domestic animals that people tend to overlook.
But people don't "know everything about" cats is the thing. Given that outdoor domestic cats are one of the leading causes of death in migratory songbirds, I'd argue that cats are one of the most important species to educate about from a conservation perspective.
As a caged exhibit animal a domestic cat would be no more of a disease risk to other animals in a zoo collection, than a wild one. The desirability or relevance of such as an exhibit, is a different matter.
All zoos have certain animals that are a zoonotic disease risk, it's just the reality of being a zoo. Responsible zoos, however, are the ones which have protocols in place to limit this disease risk as much as possible, such as PPE for zookeepers, separate enrichment items for high-risk species, and designing keeper sections with zoonosis in mind. So yeah, having a domestic cat exhibit isn't any more concerning from a disease perspective than a zoo exhibiting any other species that is a known disease vector.
The days of zoos importing species from the wild to "experiment" are over. There are not going to be Indri or hoatzin in captivity tomorrow and they will not follow the track of gorillas, a species that many zoos kept in awful, unacceptable conditions before they figured out how to manage them. We have the species we're going to have and introducing new species is largely a net negative for improving the welfare of what we already have. Space is incredibly valuable and we can't sacrifice it for silly things.
See, I don't think we "have the species we're going to have" though. Imports will be few and far between, however there have been new species introduced to AZA zoos in recent years nonetheless. Some birds in particular have become really common in zoos despite not being present a few decades ago. Examples: blue-bellied rollers (1996), crested couas (2003), Baer's pochard (2005), and scaly-sided merganser (2010). To throw a mammal into the mix, Visayan warty pigs (2002).
While new species in zoos are going to be few and far between, I don't think there is any reason to avoid bringing in a new species if there is a particularly compelling reason to do so. In some instances, for example a threatened local species, I'd actually argue zoos have a responsibility to attempt captive breeding programs when they could have direct benefits to the wild population. If Bronx Zoo didn't import Kihansi spray toads in 2001, the species would be extinct today. Surely, if another instance like this occurs in the near future, I'd hope zoos take the initiative to conserve a fascinating species.
Asiatic black bears were held in exactly the same kinds of exhibits you're showing for polar bears to argue they did not thrive. Maybe the fact there isn't enough space to house all eight bears is proof they weren't thriving, I would argue.
Yes, bears were not thriving in historical exhibits. That doesn't mean that bears can't thrive in zoos. One of my local zoos, Roger Williams Park Zoo, holds one of the six remaining Asiatic black bears in the AZA. George may not be part of a breeding program anymore, and is quite geriatric now, but nonetheless I'd argue that all of the welfare indicators show that he thrives at the zoo. He lives in an excellent exhibit with plenty of space and complexity, his caretakers provide plenty of enrichment, and he has access to the most advanced veterinary care whenever needed. There's no reason that Asiatic black bears can't thrive in zoos, and the choice was made to phase them out not due to their ability to thrive, but due to limited space.
Yes, there isn't enough space to house all eight bear species, and yes, many bears in zoos weren't thriving, but it doesn't mean that, say, the AZA-managed sloth bear, or the frequently rescued North American black bear, is any more capable of thriving in zoos than the phase-out Asiatic black bear.
Bears are a fantastic example and really represent the decline of US zoos. There was hardly a single decent bear exhibit in the United States until the nineties and now we're still struggling to get rid of the ugly concrete grottos left and right that these animals were left to rot in for decades. Polar bears are one of the best examples of a species that has persisted in captivity but never thrived. All of the data shows more deaths than births, and I suspect you'd find the same for all of the bear species kept in captivity.
Well the data for some bear species is going to be very different seeing that two of them (North American black bear and grizzly bear) are almost exclusively housed as rescues in AZA zoos. Yet if I look at the data for sloth bears, the AZA population has more or less stayed between 30 and 40 individuals since 1990. Some years might have more deaths than births, but other years will be the opposite. However, I don't think it matters if there are more deaths or births when answering the question "does x species thrive in zoos?". A rescued North American black bear can certainly live a life worth living in zoos, and so could an individual sloth bear that hasn't been given a breeding recommendation. Conversely, just because an animal is a prolific breeder and has sired a lot of offspring (say- Brookfield Zoo's old polar bear pair, which lived in one of the photos I linked in my last post) doesn't mean it was necessarily thriving.