I disagree.
What use has Nation for the outward projection of loyalty to the cause when the song of Nation (IE the constant murmer of the nearby nodes within the collective) is constantly enforcing and encouraging that loyalty, even without overt mind control.
The main purpose of having such a song in Nation would be more to speak to those outside the Unity, if anything.
First, that assumes that everybody is plugged in.
Second, it is always in the interest of messianic societies to spread propaganda not only to its own members, but also abroad.
Third, I've found nothing to contradict the idea that citizens of the Nation would not enjoy art for its own sake (in fact I've staked one of my main characters on the idea that art appreciation is high, or at least used to be, within parts of the Nation). If that art serves an ideological purpose as well, so much the better.
