Compulsory voting (along with preferential voting, a proportional senate and a permanent, nonpartisan electoral commission) is one of the success stories of Australian democracy. (Making showing up to vote — or formally lodging a reasonable excuse — compulsory makes declining to vote a deliberate act, and prevents anyone from winning merely by riling up a base of hardliners and counting on apathy on the other side, as happens often in the US.) Ditching it would be a retrograde step for Australian democracy.

Agreed, if anything I'd like to see mandatory civic classes added to the curriculum before reducing the voting age. There's no point in lowering the voting age if people fundamentally don't understand how our democracy works.