I disagree with the pessimistic note that bringing new endangered species for captive breeding is impossible. A handful of zoos and individuals are interested in that - in Europe it is the owner of RSCC and the director of Wroclaw zoo. And they manage it.
I think AZA and EAZA should cooperate more. The case of tigers is an example: both Europe and America maintain populations of Siberians and Sumatrans, but the other subspecies (Indochinese and Malayan) are hardly represented. And with popularity of tigers, there is enough places to keep populations of all six extant subspecies.
I am also increasingly critical of the current fashion of building large, fake constructed habitats, usually for one or a few popular species and at extremely big cost. I see more and more examples of totally different, much cheaper exhibits which are extremely popular. This current fashion is just a fashion, very inefficient in terms of funds and species conservation, and will pass and is not necessary.
I also think that integral part of educational mission of zoos is presenting less common animals, ones not already known from films and advertisements. There is a need of showing people that zebra is more than one species of animals, that there are more cats than tigers and lions etc. I understand that zoos need some charismatic animals, but showing nothing but them is wrong.
Since AZA talks obsessively about zoos getting most visitors per dollar of investment, maybe there is a need of active research how to make less 'charismatic' species popular? This is easier that it seems. Small animals are especially good for close interaction with visitors, and contact or feeding sessions. These are extremely popular and can be very profitable. Smaller animals can be also presented in very beautiful, naturalistic exhibits at relatively low cost.
A few things:
As to bringing new species in for captive breeding, the number of criteria needed to be met are high. I don't doubt that there are some species that could be brought in for captive breeding, but the question is whether that is necessary or indeed helpful for many species. I would not doubt that many invertebrates could be helped by captive breeding, but don't see much effort on the part of zoos to help these species (due to public interest, in many parts - even those zoos with invertebrates on exhibit do not, to my knowledge, focus much on captive breeding for conservation's sake). But the question becomes dicier with vertebrates - many of the animals most desirable by zoos are the animals for whom captive breeding would be the least desirable conservation solution (for several reasons, including problems finding sufficient space for a sustainable populations, problems sourcing individuals from the wild or private/unmanaged collections, not to mention impraticality/impossibility of reintroduction of captive individuals to a wild population in the future). The AZA is not inherently against bringing new species or subspecies in for captive breeding, but only where there is sufficient institutional interest/capacity and an identified source of a founder population (among other criteria). There simply aren't many taxa that meet both these criteria.
Perhaps it is feasible, in a perfect world, for there to be space for all 6 tiger subspecies to be managed in AZA/EAZA collections, if there was sufficient international collaboration. But this is impractical - (1) the Indochinese tiger is unrepresented in collections (as all individuals claimed to be Indochinese were taken from the Malayan population, now known to be a separate subspecies) and would require removal of individuals from the wild; (2) the South Chinese tiger is effectively (if not actually) extinct in the wild and all remaining animals are held in Chinese zoos; and (3) the Bengal tiger is well-represented in captivity outside of AZA/EAZA collections and is the subspecies least in need of help.
As to the comments about exhibit design, I'll concede that I'm not necessarily a fan of how zoos spend their money on new development, but to not see that there are a large number of concerns beyond conservation and money which lead zoos to make decisions, and I'm not privy to the information to intelligently criticize most of them. If you would elaborate more on your distinction between "large, fake constructed habitats" and the "totally different, much cheaper exhibits which are extremely popular," complete with some examples, I might be better able to understand and respond to your point.
And I would agree with your point that zoos need to do a better job with education about diversity, but not necessarily that they must do a better job presenting "less popular species." You suggest, for example, that zoos must do better "showing people that zebra is more than one species of animals" - but how does a zoo do that? Should every zoo exhibit more than one species of zebra to meet its educational goals? Or is a well-designed exhibit of a single species of zebra with interpretive elements mentioning other species sufficient? The whole point is that zoos can't do everything - in most cases, for their educational purposes, they must rely on representative species.
I don't know of any accredited zoo with a broad collection focus that does not include many types of "less charismatic" species. The problem is that zoos are necessarily limited by funding (and to a much lesser degree, space) and must make decisions on where to focus their limited resources. Many of these smaller species do not, for many reasons, make for exhibits that would be compelling to the general public. There are many endangered smaller rodents and shrews that could benefit from captive breeding, but I don't see any zoos clamoring to add them to their collections (not to mention fossorial species - is there any zoo that exhibits golden moles). While there may be a huge number of primate species that could benefit from captive breeding programs, limitations of space force some hard decisions.
In the end, zoos are mostly in the business of displaying species to the public - education and (some) conservation comes along with this. In many cases, public display is not conducive to sustainable captive breeding efforts. Many, if not most, species for which captive breeding is an essential part of an overall conservation plan (beyond merely providing a possible "insurance" population or serving an educational purpose) would not be optimally suited to public display, especially in a financial sense. And many of the most critically endangered species that have been "saved" by captive breeding have either never been on exhibit or are only exhibited to a very limited degree (e.g., California condor, Kihansi spray toad, echo parakeet).
The simple fact is, besides a few of us "zoo nerds," most of the zoo-going public would not appreciate it if zoos chose to forego the display of charismatic megafauna for the display of less interesting (in display terms), if more important (in conservation terms), species. It's simply not in the best interest of a zoo to divert most of its limited resources to the public display of less "charismatic" species solely for the purposes of captive breeding.
