Most of it is for style, the weight reduction is minimal unless it's a huge knife which of course EDC pocket knives are not. Just style and looks. Do you have pics of the culprits you mentioned?
I have a Gerber Paraframe and having hardness tested it I use for checking hardness of knives, it's a paltry Rc54 BTW. Simply weight reduction and style. Would rather have a wood or jigged bone handle, but that costs more. I will say the holes are great for catching crap in your pocket and hanging up string.