1οΈβ£ Zoos should be banned because animals are often hurt and do not have normal space and things they need like in nature.
In France, we have different way to differentiate "zoos" from some zoological parks. If you put everything with an enclosure in the same basket, then I would just say that this is very restrictive. Some areas have awful animal management, are only concrete with mistreated/undernourrished animals and those should definitely get closed and the responsible for that face the legal consequences of their actions. I remember I saw such parks in news, from Thailand, Indonesia and some alike countries that were the most extreme cases of mistreatments.
Now, you have the other edge of the spectrum, which are larger parks with half-free animals. One of the first of that genre in France was close to my house, in BranfΓ©rΓ©, where a couple of people brought back animals to their castle and tried to let animals roam as much as possible. Nowadays, you still have wallabies in the middle of tourists there.
Since then, the system developped quite a bit: Animals that can be put together are put together in large enclosure that let them move and run. There are ethologist hired to study the behaviour of each species, their personality, their habitat, and give the owner of the parks valuable suggestion like plant to install or not, if a pool is needed, what should be included or not in the enclosure, if individuals should be separated from each others (liek to avoid fights) etc. THey also think of activities and "games" to distract animals and avoid mental troubles/depression as much as possible, but also spaces preserved from tourists when animals need to chill down.
In addition, there is a legal framing with the importation of wild animals being forbidden in many cases, if not all. There are veterinaries to take care of the health of each individuals.
Something very much in favour of this kind of "zoos" is that they act as sanctuaries for extincted/threatened species. China breeds pandas for example, but that can be needed for other species as well, and some programs work on releasing animals in the wild. There is such a thing in Europe at very least. Those parks often have an aim to educate the public as well. Typically in BranfΓ©rΓ© where many things started in France, there are aducational activities as well to make the children know about the problems facing by biodiversity.
To sum up : This is a very difficult question. While there are terrible institutions and those should probably be closed for ethical/moral reasons at least (but probably for sanitary reasons as well), but there are also some parks that, while not providing full freedom to animals, are doing their best to offer a compromise between showing animals to people and acting as a conservation and educational center. Many people call everything as "zoos" despite having differences between sanctuaries, zoological park, wildlife parks etc.