I have recently noticed that many zoos do not many keep foreign small rodents or insectivorous mammals (except squirrels and dormice). By small rodents and insectivorous mammals, I mean animals such as rats, hedgehogs, shrews, mice, squirrels and dormice (no armadillos, pangolins, beavers, rats, capybara, patagonian cavies etc.). I have never seen an animal such as a harvest mouse outside of a zoo in Europe, but then what is the point in breeding (they are relatively common) them or displaying (they only live 3-5 years) them in North America for example? Personally, I believe rare and really exotic (acacia rats, flying, prevost and palm squirrels, long eared hedgehogs for example are what I consider to be really exotic) small rodents and insectivorous mammals should be kept in foreign zoos.
But zoos do keep exotic rodents. Prevost's squirrel is not that rare of a species, and the others are also seen here and there. Small rodents is not the most popular animal group out there, but a decent number of zoos have at least one or two species. Just check Zootierliste. Or am I misunderstanding what you're saying? By the way, the Bronx Zoo has harvest mice (or had - they were when I visited in 2013), so that doesn't entirely line up with your point.
I don't really understand this option in the poll: "Only rare and really exotic small rodents should be kept in foreign zoos." If only so-called rare small rodents should be kept in zoos, wouldn't that mean the current common ones would decline in populations, and thus become rare? That's just stabbing yourself in the foot. Also, what makes an acacia rat more 'exotic' than any other species not from the country it's displayed in?
I am always eager to see our native rodent species appearing in the zoos, such as several species of giant flying squirrels, ground squirrels, jerboas (especially the long-eared jerboa) and gerbils, and the "living fossil" species such as Chinese pygmy dormouse and Chinese jumping mouse.