Thank you for a very informative and provocative essay. If I may, I would like to chime in a thought or two.
I would agree that postmodernism and romanticism seem similar because both reject the existence of ‘hard’ truth. For postmodernists, though, that is due to the inevitability of subjective influences on all mental processes of any and every human being. For romanticists, the subjective is all that matters. Romanticists are therefore universalists of a kind, whereas postmodernism rejects all universals.
Also, both postmodernists and romanticists seek the ultimate emancipation. For both, that contributes to making the self the final arbiter of truth for every individual self. For postmodernists, though, with the preceding caveat in mind, ‘the rational’ is still a valid aspect of human being, if one that is not to be blithely trusted. For romanticists ‘the rational’ is an obstacle for the subjective self to overcome in its will to be utterly emancipated from any constraint it does not choose place upon itself (which, ironically, was Immanuel Kant’s position — but his “categorical imperative” was, he maintained, the constraint every human, as an intrinsically rational being, must choose for oneself).
I would add that postmodernists’ distrust of ‘the rational’ stems from their erroneous acceptance of ideology as a product of rationality (which distrust has been reinforced by Critical Theory), as claimed by ideologies’ inventors. In fact, no ideology is rational. Every ideology is based on one or more secular beliefs, making ideologies in effect secular religions, no more ‘rational’ than any spiritual religion is. (Though both equality and liberty, the ‘twin pillars of justice’ in the meta-ideology of Liberalism, are claimed by many to be found in the Bible, an atheist can believe in both equally vehemently).
What any of that has to do with ‘being a millennial’, I do not purport to know.