why the hell has somebody got to keep contributing to society after their degree? there is no justifiable principle to say that just because someone comes to Australia to study (at their own cost), they are forever indebted to this country.
moreover, you do realise, in the end, they are essentially subsidising our goddamn university system. your pity-little HECS don't mean anything compared to the full-fees they pay.
extending your argument, should Australian graduates be confined to work in Australia after they graduate? can they not pursue work opportunities overseas? if they can, then they are not paying Australian taxes or contributing to the economy.
just because i pay for the milk doesn't mean i have to buy the cow.