And then, on the other hand, when I have my signature in my trade pile (I should probably get more), I fear people are like, "Wait, is there something wrong with that abyss card? There's no number... Oh, wait, it's a signature."

I would totally collect them all if there was more than like maybe 9 Vocaloids with enough official art for them. And even including PV art, that makes it like... 20 out of 50+.