Ballistic dynamics has been considered in missile design from the beginning, but it is used in the passive phase of the missile.
There is no "why not" point of view.
Screenshot of the paper "Real-time trajectory sliding processing method based on dynamic constraints"
Why not use it in the activity section? The conclusion of this paper is also explained.
At the same time, a screenshot is taken in another article, "The Role of Guidance Trajectory Dynamics Analysis and Dynamic Characteristics Analysis in Missile Overall Design".
In other words, ballistic dynamics is a rational equation to study and calculate the theoretical ballistic position of missiles.
Generally speaking, it is to calculate the target hit trajectory of the missile through mechanics, and then change the mechanical structure through the machine on the missile to produce a new hit trajectory.
Further explanation is that the purpose of ballistic dynamics is only to calculate the most ideal falling trajectory according to the principle of force and use it as the basis for correcting the actual falling trajectory.
Then, since only the falling trajectory is corrected, it is different from the so-called traditional missile guidance. The essential difference can be seen from the screenshot of the article "Dynamic Analysis and Control Method of Trajectory Correction Projectile".
Inertia and starlight you mentioned are both ballistic measurement techniques used in the active phase. In the passive stage, continuous detection correction (such as Pershing's radar guidance) or discontinuous correction (infrared illumination and GPS) is generally adopted, but in either case, the dynamic trajectory calculation will recalculate and predict the new hit trajectory after each missile is mechanically corrected to verify whether the corrected trajectory is effective.
For example, you ride a bicycle up and down a long slope. When going uphill, the head should be fixed at the top of the slope, and the hand should constantly adjust the direction of the handlebar because of the alternate exertion of the foot and the change of the body center (this is inertia and starlight navigation). The route is winding, but overall you still walk towards the top of the slope. Then after crossing the slope, it began to slide. At this time, there are two choices. One is that there is a steel wire directly from the top of the slope to an end point under the slope, and you hold the steel wire and slide freely. This is continuous guidance. Another option is that you first look at the end point, calculate the crosswind, center of gravity, airflow and other factors to calculate a descent trajectory (which is predicted by ballistic dynamics calculation), then close your eyes and start taxiing, and occasionally open your eyes (compared with infrared illumination points or GPS points) to see if the actual trajectory coincides with the previous descent trajectory. If not, recalculate the new descent trajectory with the newly collected interference factors, then correct the direction and continue to slide with your eyes closed.