but when you succeed it should be something like "Where we wrong to interfear with their plans?"
There is a line in the game like that almost exactly like that. I think Cait Sith expresses guilt after the missile fails to destroy meteor. They say something like- Cloud: "The Shinra's plan failed." Barret: "Damn." Cait Sith: "We've been interfering in their plans all this time...." Then Red randomly suggests going to visit Bugenhagen. They did the conversation so it'd make sense depending on how many huge materias you've collected.


From a storyline point the huge materia worked in several ways;
- Barret gets redemption in Corel and earns the town's respect again.
- Cid does to become the first person in space and accomplish his dream. He also learns that Sherra was right about the dodgy escape pods and that he was wrong to treat her that way he did.
- The Fort Condor subplot was wrapped up.
- You get a submarine! You can then use that to get the underwater key, fight Emerald and battle the Turks once more.

What isn't made very clear however is just why Avalanche are trying to stop the Shinra collecting all the huge materia. I guess they wanted the materia themselves to use in the battle with Sephiroth, or they wanted Bahamut Zero...