The fasteners you mentioned can be subject to rotation (as Gary already mentioned).
We often think of bolted assemblies on aircraft to be entirely static but they can move under certain load conditions.
For example - Under high G's, wing tips can deflect up to 1.5 inches or more depending on load and model. If the wing is deflecting, there would be a very slight movement at the rear spar clevis joint, so a castelated nut and cotter pin is used.
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Van's Aircraft Engineering Prototype Shop
RV-6A (aka "Junkyard Special ")