I'd agree that they are very unexciting pieces. Basically no stats other than +song except the body that has magic accuracy.
I do think they are worth getting except maybe the feet.
Head: Etude duration +10%.
Body: slight threnody potency increase at the expense of 2% duration.
Hands. Probably the best piece. +10% potency to Carol I, +1% nulification rate to carol II and 10% duration which carol is sorely missing. Also I believe they are the best magic evasion hands(except for the hq) in the game crushing even Inyanga+2. (Shared with some other Su3 hands for other jobs)
Legs: Minne potency+10%. A Fairly large boost for high tier minnes at the expense of 7% duration. Arguably the 2nd best piece in my opinion.. except that wilt is a thing.
Feet: While stacking evasion probably does work, the acc/eva floor kinda kills its effciency vs multiple mobs. I feel like this is probably skipable cause bard very rarely casts mambo.
That said I did buy all the nq pieces.