Diminutive Suffix - Aboriginal Influence?

The smooth vowels - The Aboriginal influence?
Aboriginal words have always had a very prominent use in Australian English. For example, Australia’s unofficial national anthem, Waltzing Matilda, uses Aboriginal words like coolibah, jumbuck and billabong. Likewise, most of rural Australia has been given Aboriginal names like Wagga Wagga, Joondalup, Bondi, Yakadanda.
Perhaps the lazy way that Australians are perceived to speak is a result of using the Aboriginal words. The Aboriginal words generally end with a vowel sound, which is quite smooth and pleasant on the ear. It is possible that the use of the diminuitive, such as shortening words like journalist to journo, was a way of smoothing over the rough edges of British English in order to gain more consistency with the smoother Aboriginal English.

*Most Indigenous Australians speak with a Broad Australian accent.

Source: http://www.convictcreations.com/culture/strine.htm#abinflu