I don't know what those songs are saying, but they're great! Comments seem to say they are "songs for the nation". You're right that many people don't care about their national anthems, but that's often because a lot of anthems mean literally nothing: they're just a bunch of supposedly glorious words. But some, like
this one, hold quite a lot of weight. Considering South Africa's history, the choice of languages and of lyrics is
meaningful and something South Africans could reasonably be proud of. This is just an example, and obviously, I can't really speak on the behalf of the South African people, but my point is that the meaningfulness of an anthem depends on the meaningfulness of its lyrics (and in some cases, of its languages).
And blood watering furrows is not something appealing to much people now, probably like
the rockets' red glare and
the bombs bursting in air, but probably less like
Einigkeit, Recht und Freiheit.