[Razengan]

While annoying to me as well (the title of this post almost seems like it was intended to invite this argument), I think it can be reconciled with by treating it as [proper noun] [noun].

As in, "PIN" is a name – not a macro that is supposed to expand to the decompressed phrase – and "number" is the kind. The name disambiguates it from others of the same kind, and the kind sometimes helps to disambiguate the name:

"Enter your number" vs. "Enter your pin" vs. "Enter your pin number"

"Go there and talk to the guy named Bob" vs. "Go there and talk to Bob"