I wonder whether this was an artistic licence to make bombing missions just slightly easier, or if it was actually designed at the time, only to resurface in WW2.
I noticed that most bombs in Rise of Flight, starting from medium-sized ones, upon being released act kinda like Tallboy and Grand Slam bombs. For those of You who don't know, those two were Super-heavy (5,45 and 10 Tonnes) bombs designed by the British to destroy enemy targets not by direct hit, but by dipping and exploding underground, creating an artificial earthquake.
And the bombs in RoF really behave like them. When dropped, their fronts immediately go down, and upon hitting the ground, it's as if they punch through to a certain depht in the ground, before detonating, causing the nearby structures to turn into the air and then fall apart upon falling back to their foundations. The only thing that is missing is spinning - Tallboy and Grand Slam were designed to spin as soon as the front went down, to increase speed and gain more energy needed to dig deep enough before detonation (How deep? About 60 to 80 metres underground).
So yeah, was this mechanic intentional, or just a coincidence?