Quote Originally Posted by Fynn View Post
But what's the point of stopping the evil empire when meteor will destroy everything and you don't have any plan to do anything about it? Honestly, the squabble with Shinra can wait. We can go back to overthrowing fossil freaks after the impending apocalypse is dealt with!

That's the thing - the party is wasting their energy on stopping someone who is actively trying to avert a real crisis for everyone on earth. It really doesn't matter that they're using huge material, since they're only using it to save everyone. They could have all easily dismantled Shinra after the fact! Thwarting their plans when those plans involve saving the world just because "they're villains" makes no sense and was really frustrating, tbh.
Cloud literally states their purpose for collecting the Huge Materia: "Hey, Cid! What're you doing!? There are generations of knowledge and wisdom inside the Materia. We're gonna borrow their powers and save the planet from Sephiroth. There's no way that we can lose the Huge Materia. You understand that, right?"

The recurring theme of the game is that the planet, Gaia, is alive. Bugenhagen lets you listen to the cries of the planet from the voices of the lifestream. It's dying as a result of Shinra's actions. They're sucking the lifestream out of the planet and killing it. Since Meteor is about to crash into Gaia, the planet needs all of the strength it can muster. And wasting Huge Materia, which are VAST amounts of knowledge and life, would be detrimental towards the planet being able to protect itself. Not only would wasting the Huge Materia limit Gaia's defenses, but it also might make the planet unwilling to allow the humans to live after carelessly destroying such important resources. That's why stopping Shinra is important, because you want to protect the planet from them so it can defend itself against Meteor. And it's also the only thing you can do right now, because Sephiroth is inaccessible in the Northern Crater.

Shinra doesn't see the Huge Materia as anything but a disposable explosive device. Much like their use of Mako Reactors, they don't care about Gaia's resources. Your party does. That's why you have to stop them.