Weird thing is, of you drop a canister into orbit it does fall into the gravity well. Why not apply these physics to at LEAST the aftermath part?
as far as the instancing in elite dangerous works, its a bit more logical as long as you are outside the gavity well.
if you drop into a ring around a planet, the rocks may lock static to you, but your whole instance is still orbiting that planet, and as such, everything you drop does not drift automatically towards the planet.
if you drop into normal space within the gravity well of a planet its suddenly different. everything falls in a straight line towards the planet. you could say the instance created is in a geostationary orbit, but not a stable one.
THAT is what i find weird, especially when its a mission USS with cargo you need to salvage - that was perfectly stable until you are instanced with it together. suddenly all the salvage starts to accelerate towards the planet. perpendicular to the surface.
probably the price that had to be paid for the "seamless" descent to the ground.