Your claim about successor fails, because, even ignoring the variance of meaning of the word successor, ‘of a country’ can simply be the implication that you ar

Your claim about successor fails, because, even ignoring the variance of meaning of the word successor, ‘of a country’ can simply be the implication that you are part of that country. The union being forged with purpose seems more about there being a purpose instilled in the union and also ‘purpose’ as the raw material being forged. The part you call cliché is perhaps not that deep, but fits within the expected patriotic idealism the poem invokes. It’s also good sonically. The ‘cheap effect’ is just more concentrated youthful idealism, of the sort encoded in our founding documents and pledges.