Hm, I agree that zoos certainly aren't necessary for caring or education. The great whales are popular even though they aren't kept in captivity. Many people love the charismatic megafauna even if they haven't seen all of 'em themselves. (pandas are quite popular in the US even though only a few zoos here keep them) While walking around the zoo today, I was thinking, lots of kids don't have parents who can or will go much out of their way to take them to see nature, and animals out in the wild. But most will take their kids to the zoo once in a while. (if nothing else, the kid might get a school field trip) I think zoos allow nature to feel more real to people. This is especially important in many cities and suburban areas, where people often see "nature" as this faraway thing you need to go to some exotic location to see. I do think there are some species that don't do well enough in captivity to justify it, but I think seeing the other animals could hopefully be enough to inspire that love of nature. And getting that feeling of "it's more real" when seeing it in real life can be very beneficial when it comes to helping endangered and threatened species. Of course, conservation. We should focus on preserving the wild populations first and foremost, but it doesn't hurt to have a backup in the worst case scenario. I certainly hope that zoos continue improving in the future. Of course there are problems, but if they can be fixed, gotta go for it.
Quite easy actually. Zoo's are there for the same reason people have aviaries, aquariums etc. It's a sort of entertainment. That's what a zoo is for. But, zoo's have gotten a bigger importance along the way. Preservation, education etc. The major issue is, there are people who feel uneasy because of their concept of 'animals belonging in the wild'. It's an argument that doesn't make any sense, since an animal doesn't have a concept of the wild or freedom. Keep in mind that even in the wild they are not free.
I think much of the concern about zoos these days is more about philosophy than other things. (though there are other factors) Basically, the idea that animals, or at least, wild animals, shouldn't be used for human entertainment, even if said animals aren't really suffering for it. That's the implication I get, anyway.
Article about the conservation-role of zoos : The next mass extinction is coming. Can zoos save the world? - The Week
Zoos can, and have done, a lot of great conservation work. Though I would hope people don't fall into the trap of "We have captive breeding so everything will be okay!". Captive breeding is a supplement, but shouldn't be relied upon to save a species entirely.
Article about the education-role of zoos : It's Not Happening at the Zoo: There's no Evidence Zoos Educate in a Meaningful Way|Marc Bekoff
Article about the conservation-part zoos can ( and must ! ) play : Zoos and aquariums: The ?front line of conservation?? | Human Nature - Conservation International Blog