Convenient hand-wave to distract from the question of wether or not it has been a mistake at all: "look, reverse-extrapolated to the individual man-year it's such a small number! Who cares about the sign!"

That hour you spent chasing an NPE? Yeah, it happened. (really not that often though) The time saved by having a single, universally accepted way of implementing optionality, even it's inconveniently always on? That's invisible because we did not live through the alternative.