My personal belief is that criminals typically conceal their intent, whatever that may be. That was the entire purpose for most stated enacting conceal carry laws, because too many criminals were doing so and they needed some way to make the practice illegal, in this case by requiring a permit or license in order to engage in the practice. This is also why several states such as my own (WA) do not require a permit for OC as they reason criminals to not commonly engage in such activity.
This is my biggest beef with Conceal Carry laws and the practice in general. The state wants to charge me a fee, and in some cases require me to engage in an otherwise criminal activity. I have nothing to hide, including my self-defense pistol.