Sustainability - why do we have to legislate it if it is 'so' good and beneficial?

There's a federal website that address sustainability issues:
http://www.fedcenter.gov/programs/sustainability/

The Sustainability Program Area includes the latest guidance, examples, and information resources to aid Federal facilities in developing and maintaining sustainable facilities and helping to develop and promote sustainable practices within their environmental programs or activities.
Both Executive Order (EO) 13423, Strengthening Federal Environmental, Energy, and Transportation Management, dated 24 January 2007 and EO 13514, Federal Leadership in Environmental, Energy, and Economic Performance, dated 5 October 2009 include sustainable practices which Federal agencies are urged to implement. In addition, EO 13423 and 13514 established the following processes and management tools to aid in the implementation of the sustainable practices detailed in the EOs:

• Identification of a Federal Environmental Executive;
• Identification of an Agency Senior Sustainability Officer; and
• Establishment of the interagency Steering Committee on Federal Sustainability which consists of the Federal Environmental Executive and the Agency Senior Suitability Officers.

Every Federal agency is required to develop and submit to the CEQ Chair and the OMB Director an agency-specific Strategic Sustainability Performance Plan on 2 June 2010. This plan is also required to be updated annually.
EO 13514, Section 19 provides the following definitions applicable to this Program Area:

• Agency - an executive agency as defined in section 105 of title 5, United States Code, excluding the Government Accountability Office (EO 13514, Section 19(b)).
  
  
• Sustainability and Sustainable - to create and maintain conditions, under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic, and other requirement of present and future generations of Americans (EO 13423, Section 9 and EO 13514, Section 19(l)).

For guidance pertaining to EO 13514 and procurement, please see the Acquisition Program Area.
For guidance pertaining to EO 13514 and chemical management, please see the Chemical Management Program Area.
For guidance pertaining to EO 13514 and electronics stewardship, please see the Electronics Stewardship Program Area.
For guidance pertaining to EO 13514 and EMS, please see the EMS Program Area.
For guidance pertaining to EO 13514 and energy, please see the Energy Program Area.
For guidance pertaining to EO 13514 and greenhouse gases (GHG), please see the Greenhouse Gases Program Area.
For guidance pertaining to EO 13514 and high performance buildings, please see the High Performance Buildings Program Area.
For guidance pertaining to EO 13514 and natural resources, please see the Natural Resources Program Area.
For guidance pertaining to EO 13514 and NEPA, please see the NEPA Program Area.
For guidance pertaining to EO 13514 and pollution prevention, please see the Pollution Prevention Program Area.
For guidance pertaining to EO 13514 and transportation, please see the Transportation Program Area.

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