Why, exactly, would NIST standardize GOST? What other ciphers should it standardize? So far, it's done DES and, to replace DES, AES. Why GOST and not Salsa20 --- which people in the real world actually use?

Standardizing multiple ciphers defeats NIST's whole purpose. The whole point is to have one standard block cipher. That, incidentally, is also the point of GOST.