The Subject of Zoos

My 2.5 year old son loves animals (like most do at this age I am sure), so we decided to head to Safari Niagara for most the day. It was a great park with lots of things for the kids to do, but it was an eye-opener. I haven't been to a zoo-like park in years and as much as I loved seeing these amazing animals, I couldn't help but feel a bit sad for them. Are these zoo parks the best place for them? I know you'll say, "no", but do zoos do good things for animals? Protection from endangerment, predators and other outdoor elements? OR maybe I am thinking too much and should just enjoy these creatures since I would never see them without these parks. What do you think?