I am very much for zoos but I think better living conditions should be enforced and enforced hard.
Zoos spur interest in youth and adults in animals and give people a look at them that they would likely never get otherwise which can lead to more support to protecting endangered species and protecting the environment.
Zoos help research and preservation of animals. Though it can never beat being studied in the wild to learn of their natures - medically it can't be beat. Medical information learned from taking care of zoo animals pays off when taking care of rescued animals from the wild that need rehabilitation. Zoos can also serve to rehabilitate some animals.
There is no doubt that there are bad zoos out there and some people who work at zoos who really shouldn't but that CAN be enforced. Not all zoo keepers are like prison guards. I have a friend that works at a zoo and she cares for many of the birds there and she treats them with the utmost love. I get photos from inside the zoo behind the scenes from her often showing me new baby birds and feeding, etc. I'm sure she isn't a rarity either.
We need to continue to push for stricter enforcement of animal welfare in zoos. We need zoos if we want to educate people, and learn more about animals in a scientific manner so we can help them in their natural habitats.