Since its debut in 1971, an anti-pollution ad showing a man in Native American attire shed a single tear at the sight of smokestacks and litter taking over a once unblemished landscape has become an indelible piece of TV pop culture. It’s been referenced over the decades since on shows like “The Simpsons” and “South Park” and in internet memes. But now a Native American advocacy group that was given the rights to the long-parodied public service announcement is retiring it, saying it has always been inappropriate. […] The nonprofit that originally commissioned the advertisement, Keep America Beautiful, had long...