Speaking of systems thinking, we have to consider our own bodies as part of the whole system, right? So sustainability -- being able to take care of the planet to further our species -- should include our own health as well as the well-being of the planet and other living things. To take that one step further, the germaphobic society that America has created is a lovely example of not thinking of the entire system -- a multitude of studies (check out http://psychologytoday.com/articles/index.php?term=20080825-000005&page=1) have proven that Americans have more issues with allergies and asthma simply because we try to disinfect everything from our refrigerators to our scissors. And just as killing bug A leads to a rise in population of bug B, getting rid of germ A (a not-overly-harmful dust mite) leads to supergerm B (a deadly virus). So we've got silly things like kids in grade school getting alcohol poisoning because they're supposed to use hand sanitizer before they do anything...yet we don't see (a) the potential for a supervirus that could wipe us all out because we've erased our entire immune systems or (b) the value that these critters actually afford us in the whole grand scheme (the full system!) of things.
So true systems thinking actually takes all the disciplines (not just design or construction or engineering, but nutrition and medicine and education, too) and puts them together instead of analyzing each one independently...what a novel thought!