In theory, Bitcoin is about creating a global anarcho-capitalist economy which can't be taxed by governments or interfered with by law enforcement (irregardless of whether it can be in practice.) It's about empowering people and dis-empowering the state. It just happens that criminals are the ones who find those features more attractive than fiat.

And it's kind of funny seeing people here get offended at the idea that criminals would find it useful. That's supposed to be a feature, not a bug.