Unfortunately that period also roughly corresponded with the rise of the middle class and lifting the majority of the population to a level of material comfort that was (at it's peak at least) the envy of the world.

Most of the worst environmental damage today is not happening in the highly developed west, it's happening in the rest of the world that - understandably - doesn't care as much about saving the local animals as it cares about catching up to the material standards of the wealthy world.