Except that there are cryptocurrencies gaining traction that have far more utility in that regard.

Monero, for example, uses ring signatures to enable a greater degree of anonymity by having x% of block transactions be complete gobbledygook. Sending someone a transaction doesn't unmask your transaction activity for them to see (unlike Bitcoin), values transmitted are obscured to people browsing the blockchain (unlike Bitcoin), etc.

Bitcoin isn't the best, or even a particularly good cryptocurrency for engaging in extra-legal activities.