Well, the main firearm for police is the sidearm. The weight that a suppressor adds makes the gun more difficult to handle. Granted, my only experience is with the old fashioned suppressors with the rubber grommets, but I don't think the new suppressors are that much lighter. Additional weight at the muzzle of a handgun may not matter in target shooting (my forte) but it really matters in tactical situations.
For a sidearm, yes, I agree. OTOH, most police aren't really using their firearms in "tactical situations", to be honest. They sure like to pretend they do, but in practice, not so much.
I was thinking more about integrated suppressors, though, not the kind that screws at the end. When you can wrap them around the barrel, they can be that much lighter, and the overall length is also much shorter. I don't think anyone does this with handguns in anything other than .22 LR currently, but there's no reason why they couldn't make a service pistol in .45 ACP like that.
Also, the new types of suppressors are much less effective in quieting a weapon. Even the volume of a suppressed weapon is enough to cause hearing damage (it's the attack portion of the envelope that causes the damage as much as it is the volume).
With rifles, a modern suppressor is really quiet enough (with subsonic ammo, naturally) that all you hear is the action of the weapon working, even with something like .300 BLK. With handguns it's definitely louder, since the pressure is going to be higher out of a barrel that short, and yes, you'd still want hearing protection... but it will reduce the amount of damage that it causes even so.
I'm pretty sure the suppressor regulations are local, not national, by the way.
It's both. Some states ban them outright (though the recent trend is to legalize in more states), but on federal level there's NFA, which requires a $200 tax for every transfer, and several months of waiting time for BATFE to process the paperwork. Plus a sign-off from a local LEO chief (or a gun trust to work around that requirement).
If anything, local police are too eager to go to their weapon to solve a problem as it is. I'm not sure you want to encourage more of it by making gunfire quieter.
I want them to have the tools that they might realistically need (i.e. handguns: yes; MRAPs: no), and to make those tools safer for me if they do have to use them. A better way to discourage their misuse would be mandatory body cameras, IMO. There's already some statistics on departments that have started using wearable cams for their officers, and the drop in police use of force, and in citizens' complaints about police abuse, are quite remarkable.