errr... mainstream scientists have this dogmatic belief that gravity holds the whole universe in shape (against the outward inertia of a "big bang"), so star wars is just part of that scientistic religion. You are more observant than most scientists, and yes, a ship in a near-planetary orbit would go fast enough to counter the planet's gravity, otherwise you'd be hovering and wasting fuel/energy; so you can't just drop bombs. Star Wars likes to emulate old war movies (WW2 & vietnam)
Ya, and it is just a movie, but I thought it was pretty ironic, and then people got sucked out into space and did not die either. What happen to the cold hard space.
I forgot about geo-stationary orbits: much further/higher away, still no nice close-up view of the planet. bombs still can't drop.