Nobody says it's weak.
But unless your enemy is sleeping is too easy to avoid.
Flares pinpoint the exact point where the bombing will strike and the plane takes too long to arrive.
Guard's button was one of the only things that made IL-2 Bombing Strike appealing, but since button nerf it's only an expensive arty call against emplacements.
You could say the same thing about Railway Artillery. High damage and easily avoided. OST doesn't Have button so would that make Railway useless?