To me, the 'minor' negatives are: battery operated so won't work every time (and with good old Murphy's Law, they could die when you most need them),
That's why proper systems on guns used for self–defense have BUIS.
electronics sometimes break (see first negative),
Iron sights break as well. I broke the rear blade on an adjustable S&W handgun sight. At a recent class I attended, an instructor had a fixed rear sight come loose, and nearly fall out of the dovetail. While electronics have their own issues, the experience in recent conflicts where just about every rifle has lasers, lights, and some type of battery operated sights has shown that in CQB situations (similar to the fast shooting required in self defense situations) they give a distinct advantage. The lights have improved over the last few years, to huge degrees.
the lasers require you to train an extra action (turning it on) in most designs
No different than a light mounted on the gun. And those have shown to be very advantageous in dark situations.
and cost (good ones are usually expensive, small ones are usually expensive).
LOL. No argument there.
Possible positives to partially counteract the negatives: help for aging eyes
They sure helped me. I'm now wearing graduated trifocals. It took me quite some time to find the right spot on the glasses lens so that my front sight was in sharp focus. Not an issue in very close situations, but at any distance longer than that, or where a precision shot was needed, it seemed to take FOREVER.
Now, with the RDS, I can see the dot clearly no matter where I look through the lenses of my glasses. AND I am MUCH better at longer shots, beyond what is normally considered 'handgun distances.' A few days ago I was hitting a steel silhouette target at 85 yards offhand consistently. With irons, even taking the time to sharpen the front sight, I'd be at about 10%.
One possible positive as I see it is that in the adrenaline dump of a defensive shooting, most people, no matter how good a shot and how well trained, will miss more than they'll hit. The police only hit about 33% (1/3) of the time in a real shooting situation.
Few police officers are 'gun guys.' I was shocked to learn when I first went on the job that there are some LEOs who, if they were not required to, would not carry a gun. Some only shoot when they're required to, at qualification shoots. OTOH, there are a few who train pretty hard, and I know a few who are, or were, world class competitors.
There are situations that are unique to police (pursuing threats, possibly shooting at greater distances) that I'm willing to grant might make most of us a little more accurate, but at best, we'll likely miss half or more of our shots. Something that might aid our aim under stress and lower that percentage is a good thing.
I've never been good at anything over 35–45 yards. Beyond 60 yards I couldn't stay on paper with any consistency. But with my RDS, I'm getting hits at 100 yards about 85% of the time, with a rest or from prone. Such a shot would be extremely rare, but in an active shooter situation, I might have to take one.
My "major" negative that makes a laser a no-go for me is: size. Most add quite a bit of bulk to the end of the gun. Even smaller ones add bulk (maybe not too much for concealment, but I'd rather take my extra bulk in a larger more capable gun than in any add ons).
Yep, handguns were designed as minimalist tools. When you add capabilities and versatility, you sometimes get bulk.
The smaller the laser the more expensive it usually seems to be.
That's the case with just about any electronics. But as time passes, the prices come down.
And of course, anything added to the end of the gun makes finding holsters more difficult.
Not really. It's easy these day to find someone who builds a holster for most gun/light/laser combinations. Many LEOs these days are mounting lights on their duty weapons. Holster manufacturers are keeping up.
The one exception, they add virtually no bulk, are Crimson Trace grips. I would consider using those, and I definitely would if they were gifted to me, but I'm not sure that the utility justifies the cost.
I have a couple of lasers on a couple of my handguns. My J frame wears a CT laser. But since I'm left handed (yeah, I know – bad eyes AND left handed WHATALOSER! lol) and I can't use the CT on anything but a revolver, because my support hand thumb blocks it. I use a different grip on the revolver. I have a laser on my baby Glock that's mounted on the front of the trigger guard. The battery is in the hollow at the back of the grip and the wire is buried in a groove machined in the bottom of the trigger guard. The laser only protrudes about 1/4" from the front of the trigger guard so I haven't had any issues with standard holsters for it. And I have a combination light/laser from Streamlight that mounts on any rail. I thought that the green laser there was going to be 'the answer' to my vision problems and for many situations it was. But in very bright sunlight, against light targets, it's not bright enough to be seen quickly, defeating its purpose. The light is too bright for some small room situations, while it may blind the target, the glare is bothersome. The light is great for outdoor or large room use though.