Bitcoin has nothing to do with increase in criminality rate.Criminality was there even before bitcoin was created.It would exist even if bitcoin dies.Criminals would love to use coins like monero ,zcash which are fully anonymous and not bitcoin which is pseudo anonymous.
That is right, though there are some reason why bitcoin is used for these kind of criminal activities. We all know that bitcoin's anonymity is the reason, which is really obvious if you will be doing a crime, so your identity is safe, but not fully safe. But I think if bitcoin is not invented, I think people are still finding a safe way to make their criminal transaction.