Lasers for whom?
For the accomplished pistolero who can double tap three different targets in the A-zone at ranges longer than most personal civilian defense takes place, in under five seconds, there would not be a need for an additional aiming/shooting device like a laser.
Most (speculation: 80% ?) civilians who carry for self defense will never reach this level of competence. The people who need the great equalizer the most--unaccomplished shooters, the old or infirm, and many women, can benefit from a laser sighting device.
The great majority of those who practice shooting for self defense will never have the opportunity to pull a trigger in self defense, so the laser should be considered more a training device than combat device.
It shows in practice how moving the gun during firing decreases accuracy, and it definitely shows how much the gun moves, which in itself is a revelation to many shooters. Knowing this can certainly serve to increase accuracy for the average shooter, laser or no. If used in conjunction with the gun's sights, the gun can still be effective in combat whether the laser turns on or not.
But the truth is, unskilled shooters in life threatening situations will not aim the gun with the sights anyway. They will point it, and this is where the laser can give them the edge they need. It can be a strong reminder to hold the gun pointed steadily at the target and keep shooting. Misses may be more obvious as the dot disappears and forces them back on target.
It's not for everyone. It is an electronic crutch that could fail. Sure, it could be foggy or smoky, but in the split seconds involved in civilian personal defense at close ranges, this is hardly a consideration. The BG is already coming at you trying to kill you, right? He KNOWS where you are, or he wouldn't be trying to kill you. The knowledge that you have a laser-equipped device pointing toward him is probably more often a deterrent than a motivational attack signal.
Deal with probability here folks, not the one in a hundred exceptions that might occur.
If you were a BG in a home in the dark of night and you heard a door open, and then saw a laser dot bounce on a wall across the room from you, and then disappear, would you stick around to find out what kind of gun it was attached to (shotgun?) or how good a shooter the laser belonged to? Or would you haul your butt out the same way you came in as fast as you could?
For those deranged individuals who don't care whether they get shot, the laser will not be a deterrent, but if it helps land bullets where they need to be for average people in terrible situations, it's at least as effective as having unused sights on a gun.
CB3