I agree you get less quality even with optical zoom, but believe most Phantom pilots aren't professional photographers. I doubt there are many P3 users who wouldn't enjoy decent quality 3x zoom capability on their Phantom, in a similarly sized package & price point, even if it isn't professional movie-grade quality. If cost is no object then optical all the way.
You don't get something for nothing. Even with digital zoom. With prime lenses (non-zoom), you trade flexibility for clearer optics and greater light gathering. With optical zoom, you trade weight, clarity, light gathering and price for quality. For digital zoom, you trade quality for lack of weight and reduced price.
Digital zoom is virtually worthless. Simply crop in premiere or other post processing app. You would get far better results as its interpolation routines are far more powerful than anything DJI could throw on that tiny camera board.