Why? Cops want them. As in "buy us a compromise pistol big enough to fight with and small enough to conceal in plain-clothes or off-duty roles."
Re gear weights: Back before my plain-clothes days, I was curious one day and piled everything I wore (a relatively "light load-out") onto a scale in the locker room. Everything, as in boots, armor, clothes, etc. It weighed 23 lbs.