[impossiblefork]

That isn't really true. There are expensive and important bits on the outside-- radars, optical sensors, etc. that could be damaged by very small things.

Even $400 dollar drones would force some kind of defensive system to start shooting if the ship is to remain usable.

The ship would of course also become progressively more vulnerable as this goes on, so I don't agree that ships have some kind of D&D-style DR that means that anything costing below a million does nothing.