They financed the construction of the dam and helped make NZ more relevant when it was even more of an insignificant island that it is now, they've provided stable, high paying jobs for a whole region for decades (when meatworks were closing right and center), these stable jobs have allowed families to send their children to university and have a decent life. Pollution wise they havent done so poorly, there is maybe some nastyish stuff buried on site, but other than that smelting bauxite is rather clean.

They produce the most 'green' aluminiy in the world, would you rather it be made with coal fired electricity?

As for providing 1000jobs, yeah, maybe directly, but those people spend money in town, not to mention the contracts Tiwai would bave with other companies in town.

The economic value has been huge.