I'd endorse the comments by @Onychorhynchus coronatus, @Maguari and @birdsandbats, it is possible to see many species in the wild once you know where to look. Further there are just so many more species out there that are never seen in zoos, and never will be.
I'm not against seeing animals in the wild (in fact, I consider it to be a rare honor), but it is definitely more expensive, carbon-intensive, (and sometimes dangerous) to travel the world and traverse the wilderness to see species, an activity often limited to the wealthy. Zoos make animals more accessible to the public, especially for lower-income urban folks.