Okay, let's compare it to: Let's not make auto-pilot mandatory in planes, because sometimes a copilot has found that a pilot was drunk when taking off manually.
Even if there was a drunken pilot epidemic that causes 10 plane crashes per year, and autopilot only prevents 1 plane crash per year, it would be ridiculous not to make the autopilot mandatory and rely on its absence to catch some of those drunken pilot crashes.
In the example you give, if the copilot catches the pilot more than 10% of the time, then the swap to mandatory autopilot kills more people than not doing it.
I hardly think it would be ridiculous to want to save more lives.
Even if there was a drunken pilot epidemic that causes 10 plane crashes per year, and autopilot only prevents 1 plane crash per year, it would be ridiculous not to make the autopilot mandatory and rely on its absence to catch some of those drunken pilot crashes.