There are actually many more "dwarf" continents (the usual name is microcontinent). The Kerguelen plateau and Madagascar are the two other large ones, as far as I know. Australia and Antarctica are much larger, and in fact microcontinents are defined as being smaller than Australia.
Zealandia is just in the news because it's the latest one to have been formally called that, possibly because it's the largest one (but not enough to be in a different category) and probably also because there's an English-speaking country on it. But it's actually not especially notable.
Zealandia is just in the news because it's the latest one to have been formally called that, possibly because it's the largest one (but not enough to be in a different category) and probably also because there's an English-speaking country on it. But it's actually not especially notable.