Actually, from a roleplaying point of view an MC makes a lot of sense for this type of game simply because, as a biker, you can operate/play both sides of the fence. You can take part in everyday life and, if you are actually a criminal, take part in activities outside of 'normal' everyday life.
In most games 'criminal' is just an excuse for causing mayhem, players who often wear that tag can't seem to grasp that criminals should actually try to operate under the radar......i.e avoid being KNOWN as a criminal,, let alone avoid being caught. IF (and thats a big if) MC's are run as they should be in Identity then they are the perfect cover for crime, because, in reality, not everyone in an MC is actually a criminal. However, if MC's are run just as crime gangs, then yeah, there will be problems.