Yeah, "populate or perish" was the old catch cry. Sure, bring in you 200,000 migrants but unless we as a country feed them, provide clean air and water it's a mute point.
Australia is an arid continent with the majority of its population clinging to existence along the eastern seaboard which by sustainable standards is already over populated.
By all means throw open the doors to the rest of the world however your children and grandchildren won't thank you.