Why not? Because the panda is perfectly adapted to living in bamboo forests, and when the forests are cut down the panda has nowhere to go. Its not a matter of the animal not choosing to adapt to what man has done to its world, but it physically can't live apart from the bamboo for a diet.
We wiped out many species before we realized what we were doing; today we manage to live just fine without the Passenger Pigeon, the Carolina Parrakeet and the Great Auk, to mention only 3 species that once were plentiful in the USA, but is it really OK that we killed them all off?
Maybe there is a time for any given species to die out, after all species have been coming and going since the world began, but who are we to decide that, or to carry out the elimination?
Somehow I think that the world would be a poorer place without Giant Pandas, Snow Leopards, Whooping Cranes, Right Whales or any of the other species that are teetering on the brink.
And I rejoice that we were able to save the buffalo, the Peregrine Falcons and the Bald Eagles before they went over the edge!