Comment: Because of the following:

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Because of the following:

Promotion of nature-worship
Promotion of a goofy Gaia-hypothesis crap-brained worldview
Insinuation that industry is inherently evil
Treats capitalism as evil - it's a CORPORATION, not government, and even though we all know corporations get their power from government, everyone else thinks they're proof of how bad capitalism is.

In short, it's a ridiculous, anti-human, nature-worshipping, and philosophically half-baked.

That's not even getting into the absurdly flat characters and the fact that getting the mineral would be incredibly beneficial to humanity's chances of survival, as well as the fact that the movie had to pull a blatant Deus Ex Machina out to give the movie a happy ending.

Also this: http://sluggy.com/comics/archives/daily/20100204