Why is a private currency important?

Privacy is not about doing illegal things. It is about:

  • Not letting you ex-wife, your son, you boss, your neighbour or (particularly if you are a company) your competitor know how much money you have, where it comes from and what you doing with it, forever (and no, multiples addresses or mixers or tumblers just don't work).
  • Help journalists in dictature to lower their risk
  • Avoid being incriminated because your money was tainted (two transaction before, it went from drug dealing, for instance)
  • Act freely, because countless studies proved that people behave differently when they know they might be watched.
  • Having more privacy than with a bank, not less

Some more detailed answers: