If your salary is in Bitcoin, do you want that out in the open on the public Bitcoin ledger?
Fiat currency has privacy because there are laws preventing your bank, for example, from openly publishing how much you have and how much you get from your employer.
These privacy coins are attempting to bring that type of privacy to the cryptocurrency market.
Fiat currencies are not private at all! In fact most banks are required to KYC heavily and for sure to report to the government all information. Privacy is more related to governments than to you neighbour knowing your salary.