We're in this together.
The question was posed: "Why should the Australian Aborigines have to give up their culture and way of life because this land was taken over by Europeans?" The same could be said about any number of cultures lived by indigenous people before their land was colonized or taken over by those from outside. It is a legitimate question in some context but it can be used for guilt inducement, not as a call for justice. It needs to be viewed in other ways, as well.
One answer it that the same thing happens to ALL of us. It's not always so obvious, but it's going on as we sit here. Things are changing in the world, changing the way we live whether we like it or not and not always making things better. Change is not always fair or good, but it is part of the human condition. It may not be by physical invasion. Technology invades privacy. Modern employment patterns intrude on private and family life. Alterations are imposed on us, not always for the best. It can be inaccurate to point to certain examples only.
If you want, you can keep the superficial aspects of the past. That's what the rockabillies do. They still have Bakelite radios and other things from a past era. But if I'm rightly informed they also take advantage of modern medicine if needed. So be it. They are allowed to dress in period styles if they wish. They should be, too.
If people want to really avoid being affected by the changing world, then in a free society you can live as the Amish do. They eschew modern technology, drive horse drawn buggies and live without telephones or electronic media. It can be done, if not easily. Important to note is that the Amish are able to do this because the wider nation around them, the United States, protects them and their right to live as they do. What they are avoiding also confers certain protection on them. That is worth considering before people beat up on Western civilization.
In Australia, there are still settlements where Aboriginals live their traditional way, or as close as they can or choose, and likewise, that choice is given them because the modern nation of Australia allows and even supports them in doing so. There have been cultures in the past who were completely swept away by invaders, or just by circumstances changing. The original people of the Chatham Islands, off New Zealand, were wiped out by the Maoris, who came later. The original inhabitants of the Caribbean Islands were wiped out by the Caribs, who were there when Europeans arrived. No-one was there to stop the complete annihilation of a people in those days. They are gone from the world forever. Other indigenous or First Peoples survive because the modern nations that formed over them now protect their right to keep their identity. The Australian Aboriginal people survive as an identified, ongoing people because a modern nation which invaded their land now protects them. There are Aboriginal communities in inland Australia which continue to live in the traditional way, or as close to it as they choose, but the certain added things like cars, mobile phones, alcohol and Western medicine. There were some abominations in the past, with massacres of Aboriginals, stealing of their children, and racist rejection of some who tried to adjust to European society. It does not undo that or cancel the misery it caused to say this, but it is still true that such things happened everywhere on Earth. It is a good supposition that any human being alive today had some ancestors who were invaded, and some who were invaders. The conclusion to be drawn is that the world forces change on all of us, some of it good (like forbidding infanticide?) and people such as Aborigines are quite prepared to take up those parts of European life that suit them. The world we are all born into has been wrought and shaped by all sort of horrors and evil, as well as some humane changes and progress. We all have to live with what we know, and try to avoid repeating the same mistakes. We all might wish we could bring back the past, especially if it is romanticised.  The hippies of the 1960s wanted to go 'back to the earth'. Before the Industrial Revolution most people did live close to the earth. They lived in villages, small agricultural settlements, and farmed. The coming of industrialization changed that.  There was much misery in the process, too. But if you REALLY want to go back to the earth, to the past, give up your mobile phone, the internet, antibiotics, access to kidney dialysis, and modern surgery.  Get the point?
The age of King Arthur is over for Britain - if it was really so good.
The age of Brian Boru is over for Ireland - if it was really so good.
The age of Pemulway is over for Australia's first people - even if it was really so good. What happened in those days to people who developed glaucoma or cataracts? Did traditional healers have effective remedies? What happened to a child born with hole in the heart? Could they treat it effectively?

History is full of sadness, All our ancestors suffered. We all have to endure change, whether or not we benefit from it. Sometimes it is for the worse. But look at the wider context to understand it properly.