Why equity (must be addressed)?

A problem came up when I was reading a book about sustainable business. That is, why equity must be addressed when pursuing sustainability.

A quick answer is that failure to make resource and product equal to people will lead to social unrestness and ultimately threaten the existence of the business. But are there other reasons? What else should be allocated equally?

It was found in research that inequality can perpetuate poverty and hinder cooperation between groups of different social status. Inequality can lead to reduction of production (Daily and Ehrlich, 1996). Besides, economical inequality also impair the market as the demand will be curbed as less people have enough purchase power.

The equity between generations is itself a core implication of the sustainable development paradigm.  For certain issues, the distribution of impact and distribution of efforts and responsibility also influence the incentives of various parties.