Also if you care about national interest, it would be counterproductive to "shut up" or forget about past failures for an ego boost. That would make the country detached from reality, isolated from the rest of the world, and prone to the same failures.
Last but not least, it's very insensitive and inconsiderate of you to label South Korean trauma as a mere "political crutch" or the Dutch colonial past as no longer "relevant." Historical injustices can carry on to today's injustices much more than you think. You should try to see the perspective from the other side more before dismissing these things.