The main reason its only for illegal activities right now is because (for almost every case) it provides no advantage over using a credit card. The biggest pro

The main reason its only for illegal activities right now is because (for almost every case) it provides no advantage over using a credit card. The biggest problem is the user now owns liability. With a credit card, if someone steals your card you can call up the provider and get the charges reversed. Without a centralized authority, if something goes wrong with your bitcoin account your out of luck. Other than that, its somewhat inconvenient to get your hands on it. BTC exchanges feel a little shady. And it's not as private as you'd think. All of your transactions are public. On the plus side, you don't need a credit card provider to bless your business, so sketchy or illegal businesses are free to transact online now. And lastly, it's decoupled from any one government. But that's not a benefit unless you live in a volatile region.