I'm not going to argue the merits of Zoos here. However, let it be known I strongly disagree with the OPs evaluation of such a complex problem and his overly simplistic solution.
About the tiger attack, I strongly suspect that the recent attack is caused by someone harassing the cat in question. Since many of these animals are often harassed by bratty little kids, retarded (not the special kind) adults, and moronic foreigners*, it comes as no surprise that such an animal would eventually get pissed off and go on a rampage.
I was recently at the San Francisco zoo (yes same zoo) and some stupid ---fudgesicle--- was throwing crap into the gorilla enclosure to try and entice the gorillas to come out. At the bear enclosure, dumbuck kids were hitting the acrylic viewing pane as hard as they could to try and get a sleeping bear to move. Come to think of it, if I know which cat it is, I think I saw this particular cat in the cat house (a medical holding building?) and it was definately distresssed. It kept walking in circles and hopping off the doors. The same exact behavior my cat does when it gets cabin fever and wants to go outside. When I was there, two idiot foreigners had ducked under the safety rail and were standing within paws length of the cage. Fortunately, a Zoo attendant rushed up and kicked them out.
*Not saying all people from other countries are morons.