I think you misunderstood quite a deal when you visited us. As a whole we are a multicultural country, however, the Aborigines have a history markedly different from our 'modern' cultures. In short, they were semi-nomadic, very tribal and had absolutely no concept of ownership.
Enter the white man. We see these people living without clothes. So we give them clothes. We see them without shelter. We give them shelter. Unfortunately, we failed to understand that these concepts don't mean much to a people who live, literally, for the land itself.
From an Aboriginal's point of view, we white people live off the land by harvesting and digging and, basically pillaging the earth, but are completely disconnected from it. They simply don't want to live like us, and yet we force them to (mainly because we don't understand).
Tragically, we have forced them to live in sheltered areas, wearing western clothes and even worse, they (somewhat like the american indians, from what I understand) also have alcohol issues as a result.
There is no easy answer for the Aboriginal issue, since there doesn't seem to be a culture anywhere else in the world similar to them. Unfortunately, we seemed doomed to make mistake after mistake trying to interact with their long lived heritage and culture. It has nothing to do with Immigration policies.
Note further, that there are Aboriginals who (while still acknowledging their heritage) now live in a 'western' manner: clothes, house and job. Many many are very highly educated too. We white people see them as a success, whilst many Aboriginals see them as brothers who have lost the way.
I hope this helps.