I'm in favour of well designed, well maintained, well funded zoos with competent, enthusiastic animal carers and well trained support staff who can provide for most of an animal's needs. Plenty of space in enclosures, representative of the animals typical habitat is important.
I believe that zoos should be a comfortable, pleasant home for animals. I also think that zoos can be an exceptional venue for public education about the animals...their characteristics, their needs...their past, their current status...what the future may hold for them.
I'm fortunate to live in a part of the world...western Canada...where I'm close to a number of different topographical areas. I live on the extreme northern plains of North America...but I'm also a couple of hours driving (northwest) from the boreal forest.... then 90 minutes east takes me to the Canadian Shield and in the extreme northern part of my province (quite a distance) is the tundra...Hudson's Bay ...with Polar Bears, Barren Ground Grizzlies, etc.
It's not a province that has a huge population, considering it's very large area. Over the years, I've gone on a lot of trips throughout my province and one result has been the opportunity to see grey wolves, elk, black bear, moose, bison, pronghorn, a plethora of various members of the weasel family, etc... all sorts of raptors...even a sighting, once of a wolverine...all in the wild.
My wife and I have also been to places like Yellowstone and we've seen a number of people there...who I assume are from large urban areas...far away from any wilderness and at Yellowstone they're able to see...often for the first time... wild animals in their natural habitat. Which is good, although at a large national park...sometimes enthusiasm at seeing a wild animals, maybe for the first time...overtakes good judgment....about how close one should get.
My take on the questions posed by the OP......zoos are good...as long as they're well run...see first few sentences in my post.
They can provide safe, educational opportunities for many people to see first hand...other residents of our planet...to ask questions, appreciate the diverse richness in animal species we have on our planet.
Good question aslyfox...and an important question.