In part, that's because of a 2016 reimagining of the MacBook Pro that didn't stick. Atypically, Apple then went on to reverse many of the changes it had made. The fancy function-key replacement known as the Touch Bar went bye-bye. And several mundane-but-useful features Apple had axed came back, including the MagSafe power connector, HDMI port, and SD Card slot.
Sure, the original name was confusing (is 4K better or worse than 4K Select?), but a mere name change in a lineup of four identical gadgets isn't enough. It assumes you're willing to do the mental gymnastics of recalling where other "Plus" products sit in their respective lineups, and what that might mean for this device's capabilities. It doesn't solve Amazon's biggest problem, which is that it still sells three 4K-ready sticks within $10 of each other.