50,
I think you're dismissing the laser too quickly.
In situations where the lighting is starting to go, it can be quicker to acquire than iron sights. Used in conjunction with a good light, it works better than iron sights in darkness.
Using a laser automatically focuses your visual attention on the target. You look more at the target threat than the sights, and you may tend to see more of what the target's doing, such as hand activity, and so on.
It also offers the option of firing from any position (hip, under arm, etc) without the use of sights.
I don't recommend firing from those positions as first choices, but (this from a police viewpoint) if you're walking at a low "assault" position with the shotgun either at the hip or under the arm (much more comfortable than a low shoulder-ready position for extended periods), the laser can acquire a sudden threat quicker than bringing the gun up to the shoulder for a sighted shot. I find in myself, and did with others when I was an instructor, that firing from either of those two positions typically results in the pattern going high. Using the laser dials the pattern right in from any unconventional position if you have to use one suddenly. No guesswork.
I disagree with you in your broad statement about shooting more accurately without the laser. In darkness it's not easy to achieve a perfect sight picture even with a light, you have to line up three sighting points (both sights + target) and your eye. Using a laser in conjunction with a light, you put the laser on target and if it holds still (we're talking static accuracy) it's easily repeatable without lining up any kind of a sighting plane with your eye.
The laser is an adjunct, it's not there to be the main sighting system. And, of course, you're right on its limited usefulness in daylight. If you've got decent light, and you're in a high ready position, you most likely will acquire a target quicker with irons.
If you feel you do better without one, that's OK, but I think lasers have their place.
Denis