I have a working theory, and a bit more info. All of the abilities you have listed have a new UI behavior, where they "light up" under certain circumstances, and their behavior changes a bit. Aimed Shot gets a fire-like highlight when MMM is up, and the traps get the same highlight after you have cast trap launcher. My hunch is that there are actually two spells. When you macro "/cast Aimed Shot" you are actually casting the version that has a 0-second cast time, NOT the version that has a 3 second cast time.
To further demonstrate this, if you are MM-spec, create a macro with just "/cast Aimed Shot" and drag it to one button, and then drag the aimed shot skill to another button from your spell book. Right away you will see that the macro'd skill is grayed out, and the raw skill is not. Now go to town on a target dummy, or anything, and when MMM procs, note that the macro'd skill becomes active, at the same time that the raw skill gets a highlight, and then it will become inactive again.
While this is odd, there is a *possible* application of this that is very useful. You can use the above macro-button, mapped to your shot priority keys, and this will keep you from accidentally triggering the 3-second cast for aimed shot
NOTE: I've seen in another thread that when a macro'd AimS is used, it always generates the cast time, so I need to validate that.
Does anyone know if there is a way to macro the initial-state skill? I think I saw a blue post about this in relation to warlock skill, which would indicate there isn't a way to do this.