The danger lies in the authorities perceiving it as a medium for criminal activity, especially significant amounts of criminal activity. It is one surefire way of getting bitcoins and its exchangers persecuted by the law and exchangers potentially prosecuted. Even suggesting it, can be enough for conspiracy charges especially if the government has it in for the system or its exchangers and users.
Good business decisions money wise, often involve illegal activities. This can be seen regularly in the news. However good business practices such as staying out of jail and staying in operation especially long term require following legalities.
The problem is inherently, as I have stated elsewhere the less morally reprehensible the act the harder the state cracks down...
The state went to war on American civilians on two occasions less than 20 years ago, over alleged (unproven to this day) tax discrepancies totaling less than $250 combined. In both cases the state fired first, and then proceeded to execute with extreme prejudice. We do not see this type of action taken against drug cartels, prostitution rings or any other illicit activities, just ones that the average person would not generally look on as such a bad thing. The state then used media to propagandize the situations to some monstrous proportions, the first was based on a racial issue that did not exist, and the other was claims of religious sexual practices that did not exist...
In effect they legitimized state aggression based on people's emotive decisions on non-illegal actions, not that these non-illegal action existed at all...
The strength of this is the decentralized nature, there is no one place to attack that will destroy us all...