Originally Posted by
The Crystal ^ Hard to see the good guys using Materia:
-According to Nomura, the use of materia drains the planet's life energy, this being why the good guys don't use it anymore. There's not an explanation for why its use drains the planet's energy, but based on Sephiroth's explanation from the original game that materia links someone to the planet and allows them to use its powers, its most likely that the materia allows someone to tap into the Lifestream's energy and manifest it as a spell based on the specs of the materia they're using. This would, of course, drain the planet's energy, the same as turning it into electricity would.
Hypothetically speaking (since I can't really contradict Nomura...), I'd think that the manufacturing of materia would tend to drain more of the planet's energy than anything. I mean, what would happen to the energy after the materia was used? I'd think that consumption would happen in the refining to mako and/or electricity process instead of channeling the raw form. Didn't the Ancients use materia?