Cryptocurrencies, fiat or other monetary instruments are just tools. Ideally they should work equally well for both criminals and non-criminals. Once you start building in features that would make it harder for the criminal-of-the-day to use the tool then becomes a piece of shit.
Exactly.
Take a screwdriver for example, just a normal tool in the hand of a non-criminal. Give it to a criminal and they use it to bust open the ignition when stealing a car. All depends on how it is used.