So, looking around the Guide to Warfare, and deciphering some things about the music from RC, I'm going to make a guess here:
All the lyrics from all the songs were taken from, adapted from, or otherwise inspired by a speech given by this Rexutu the Unconquerable before the battle of Zhell. He's described in a manner that makes him seem like he's either the leader or at the least a major hero figurehead to the Taungs, perhaps the successor of that Doom of Ulmarah that was mentioned. The battle was pitting the Taung forces against vastly numerically superior Zhell forces, and when you go into the lyrics, they often seem like what one would say to psyche up your forces for a suicidal battle. Now, if this is correct, it means that this battle, it's leaders, and certainly it's cultural impact have been remembered relatively clearly for over ten thousand years, since Jango thought it appropriate to make this (certainly archaic) set of songs the GAR anthem.
Now, it might have just been a RL artistic issue, having so many repeat lines in the music, but perhaps (given what we know about the peculiarities of Mandalorian memories) it makes more sense for it to simply be a particularly strong ideal within Mandalorian culture that, in my opinion, has been left a little underdeveloped in the long run.