But it's not really used to further the story or develop the characters, at least not the planet-destroying part of it. Han and Finn went there to rescue Rey, not to destroy or sabotage it. The fact that it's about to destroy the Resistance's base is at best just peripheral to the main conflict with the characters, and at worst a distraction. They could have taken that part out with only minor changes to the third act, and they probably should have.