I don’t know about any other flashlights, but I have a minimag, you have to twist the top to turn it on and then adjust the beam.
If you’re out hunting, that takes precious time, especially when it’s also mounted to your gun.
So if you install a tailcap switch (with or without remote) you can leave the “head” at its optimal position and switch it off and on without having to touch it.
As you can imagine, this cuts down several seconds between spotting your target and the pellet smacking the hell out of it, which also improves your chances of having the latter actually come true 😈
Again, I don’t have a clue how other lights or lasers operate, I haven’t really put any research into it yet, as I don’t hunt at night… yet 8)
Like bart says, it saves time, but it also eliminates some movement that might give you away. You can already be almost set up for the shot, and you don’t have to move your hand to turn the flashlight/laser on.
Using the switch allows you to put the crosshairs in roughly the right place using ambient light or whatever, and then briefly turn on the flashlight, line up crosshairs while the animal is still “WTF is that” and take the shot with minimal movement and any kind of speed.
Its quite fiddly trying to do the same thing with a clickie or a twist switch.