That'd be my sentiments. The US carriers have already shut down 3G, as of a few years ago.
Sure, it caused some issues. For example, security systems that relied on 3G networks were made obsolete. Yeah, that sucks, but it's not actually a good reason to maintain
costly old infrastructure that's supporting just a tiny group of people -- unless it's truly necessary.
In my country, they're trying to phase out the old wired phone system. I'm not really okay with that, but that's because there are still people who can only get a wired phone system. They don't have cell service where they live. They can't just buy a modern phone (most major phones sold over the past decade, or longer, as 4G is still available). They would still have no service. 2 to 3% of Americans still rely on a landline telephone.
I'm okay with phasing out the old wired phone system after those people have a reasonable alternative. (Having used it, I'm not sure that I'd call a satellite connection 'reasonable'.)
I'd like to keep the old system in place. It's a very, very robust system. Back when I had DSL, I saw the phone lines on the ground and encased in ice
while I still had a perfectly fine connection to the internet. It takes a lot to take out phone service.
But, I also understand that it's expensive to maintain and that it is no longer making the profits it once did. In fact, it may be a cost center for the carriers. So, maybe there's a path to making it a true public utility.
Also, there are laws (in my country) that apply to phone lines that do not apply to cell phones. I won't get into the weeds with this, but cell phones aren't required to offer universal coverage (plus there are state-specific laws).
So, I have (what I feel are) legitimate reasons to want copper phone lines to stay for now, but that is (in my mind) a very big difference between the two situations. These people/products can be updated, and probably should be updated. There's no good reason to keep 3G around. Additionally, and equally important, those people have had ample time to upgrade. It's not like this is some sort of surprise.
But, again, I can't speak for Australians.
The people complaining remind me of Luddites. (Let's hope they don't behave as the Luddites did.)