Its interesting to remember that DYRL is actually a movie within the macross continuity. Hence, it is actually a work of fiction as compared to the reality that is the TV series. Whats interesting to note here:
The songs in the TV series (actual history) are all Minmay’s songs, composed by her or for her by other human beings.
On the other hand, in the fictional movie, DYRL is a song created by the mysterious progenitors of both humans and the zentreadi.
Songs in macross are merely representations of culture. In actual history, the zentreadi were defeated by/succumbed to human culture.
On the other hand, the deliberate inclusion of the detail of DYRL as a song belonging to the progenitors of both races changes a lot of things.
In actuality, the zentreadi accepted and tried to adapt to an alien culture that was, for all intents and purposes, anathema to their own.
On the other hand, DYRL posits the zentreadi acceptance of culture “remembering love” as a reclamation of their own lost heritage. The zentreadi are no longer discovering a new way of life, but are rather REdiscovering a way of life lost to them since time immemorial.
As such, it may be interesting to think of DYRL as a form of propaganda to ease the cultural tensions that were prevalent on post war earth and to stem the zentreadi rejection of human culture as alien to them.