Pages and pages have been written about why Australians obsessively shorten words, but I think it must be a reflection of Australian culture and how Australians see themselves. Culturally, Australia is very informal with a strong sense of shared heritage and camaraderie. As with any culture, hearing someone speak in the same distinctive way is a way to feel that you belong.
I'm not sure but I think the environment must have played some part in this tradition. Although Australia is about the same size as the contiguous 48 U.S. states, it's technically an island (an area of land surrounded by water). Any isolated country is almost certain to develop its own distinctive language and traditions!
