What resources do we have, on this planet, that cannot be obtained for cheaper by simply mining asteroids or uninhabited planets?
Seriously, folks. There's only two advantages to obtaining resources from a world with native inhabitants more than willing to destroy themselves and their planet's habitability in self-defense, and that is if the planet either 1): has resources found nowhere else in the system, or 2): you need refined products, rather than raw materials. Based on the composition of Earth compared to asteroids and other bodies in our solar system, 1 is out the window (after all, there is a REASON they're callled Rare-Earth elements), and 2 is patently absurd for any interstellar-faring species.
To say nothing of the fact that its almost infinitely more expensive to drag mining equipment (and the ores, or, even if you have refining facilities on the planet, the refined materials) in and out of the gravity well of a planet as massive as Earth, than it is to simply get whatever you need from the nearest belt of lumpy rocks. That is physical fact. Nothing will ever change that.