@ julian
Releasing captive animals is very difficult. They have to be deemed releasable by the appropriate authorities, and animals must be placed in a release program. They have to be trained to be wild again! Raising all animals without human contact will greatly limit enrichment and research opportunities, so that isn't a viable way of going about it.
Not every facility has the means to do an extensive release program on their own, and the species has to be approved for release attempts. But facilities can work with other facilities in breeding programs, research, and educational outreach. Conservation is much more than just releasing.
Regardless of your view on cetacean captivity, SeaWorld cannot release their whales. They aren't even legally allowed to. The animals they have need to be deemed releasable. Some of their orcas, such as Corky and Ulises, have been in captivity for decades. Putting them in the ocean where they will be exposed to foreign pathogens, fluctuating water temperature, and in a very unfamiliar place is not the best idea. Just look at Keiko. He disappeared for a few weeks, then appeared in Norway allowing kids to ride on his back. There were unsuccessful attempts to integrate him into a wild pod, but he wanted to interact with people instead.
Release is a lot more complicated than you think it is.
The captive orca lifespan is a bit tricky. It is important to note that orca captivity started only about 60 years ago, and only in the past couple decades have they've been kept with success. There isn't enough data currently to say whether or not they live shorter lives than their wild counterparts. There are no recognized orca subspecies, only ecotypes, and most captive orcas in the US and Europe descend from Icelandic whales. They do not have the kind of "language" that we do, but they do have unique dialects. However, cetaceans can learn the calls of other species of cetaceans. I'm sure they can communicate with members of their own species just fine. And wild orca attacks have happened. Just pretty rare because people aren't out swimming with them as frequently.
But I totally agree that people shouldn't take animals out of the wild to be pets, and I couldn't agree more that animals in the wild need to remain wary of humans. It frustrates me to no end seeing people swim with wild cetaceans, for example!