It definitely needs to be there. Reason is, due to the unique shape of the throttle pattern, (the "h" pattern), if someone was in low idle, and didn't know it, and then tried to go into reverse, they would inadvertently move the throttle from low idle to fuel cut off. And vice versa (if they were in high idle and thought they were in low idle, and wanted to go to fuel cut off, they would instead go to reverse thrust.)
Even if we made it an option to toggle it on or off, there would be people who would simply forget to toggle it back on when needed. All things considered, it's best to have it intermittently appear (only when using the throttle.)