I well understand the reasoning behind the 2nd. I simply find the initial reasoning to be unrealistic in todays world. In my opinion anyone who believes the United States Gov't could become a police state, or corrupted to the point of tyranny is misguided. Added to this would be the result of any armed revolution, which would be quickly put down by the forces controlled by the most powerful military ever to exist on this Earth.
I personally do not see a need to arm the population as a means of protecting it from the Government, as there is literally no chance of defeating it should it decide to destroy us all. And, having such weapons in the hands of my fellow citizens seems far more likely a danger than the U.S. becoming a dictatorship bent on my destruction.