Eh, yes - I just explained why: the poll doesn't support your claim that many people "no longer believe what the IPCC says".
I don't imagine that those people believe the IPCC but disbelieve everyone else, as the poll doesn't say, but if you want to argue that case then I'll certainly try to facilitate you.
Why it matters is because individuals have votes. And if a large number of individuals, as the polls show, believe that the threat from global warming is exaggerated, then they are likely to do as the voters in Queensland has just done, and kick any political party who wants to impose taxes on them in the name of climate change.
I think I am right to say that Australia is the first country in the world where unpopular environmental policies have become a political game-changer, and that is why it matters.