No, Kangaroos are not significantly damaging crops in Australia, because Australia is a large country. The amount of damage done by kangaroos in the country is small, compared to the amount of area there is, and the amount of farmland that there is. Kangaroos are not enough of a problem to warrant taking any action.
I feel like Kangaroos have always been a part of Australia. They're part of the ecosystem, and I feel like getting rid of them, or limiting them could hurt that system that works so well. Instead, there should be more protection over crops, and other resources they are capable of reaching.