"Things You Wouldn't Know If We Didn't Blog Intermittently."
Just to give it heft and make it feel more substantial, no doubt. Like when it turned out Beats by Dre were weighted for no reason.
That size of flashlight is favored by security guards, and they are trained to use them as a 'billy club', a hand to hand weapon, because of their heft and size. Replacing the D size battery's with a small recharge pack, lowers the weight and effectiveness as a weapon, so, just as they used to fill small bags with lead to make a black jack, someone has used a concrete plug to increase the weight back up of the flashlight.