Most people, here and elsewhere misunderstand what the militia is and what it's purpose is, and yes, there is definitely a point to them.
The American media has successfully convinced most Americans that the militia consists of small groups of "military wannabe gun nuts" who run around the woods in camo outfits. This is blatantly wrong.
The "militia" is the armed citizenry of their respective states (and the nation). The militia exists in two parts, the "organized militia" (which is the National Guard), and the "unorganized militia (which is everyone else). Both the organized militia and the unorganized militia are at the call of the Governor of their state - and during times of national crisis, the President.
The various "militia groups" are part of the unorganized militia who have decided to meet regularly to train and associate with those of like mind. They have no "official" authority or role except when called by the Governor - but they are not doing anything illegal and are not a threat to the community. Naturally, there a few nutjobs in any organization, but that is not the norm.
During times of war (foreign assault), the nation's first line of defense is the "standing army" (i.e. the military armed forces). The second line of defense is the "organized militia" (National Guard). The final line of defense is the "unorganized militia", which would inlcude the various police agencies.
During times of peace (civil disturbance), the first line of defense is the police. The second line of defense is the National Guard (as directed by the Governor). The third line is the unorganized militia.
Short of massive foreign invasion or widespread rebellion against the government, I can't imagine any scenario where the "militia" groups would operate independent of some civil authority. In a SHTF scenario that required militia support, they would most likely be assigned to a National Guard unit, or at least placed under the authority of a NG officer.