Laser sights are good in principle. They provide very accurate shots on weapons, namely guns. However, they have one fatal flaw, they give away your position. This is not something any reasonably trained sniper would wish to do on a daily basis. Following a laser across a wall (or your body) will let you know exactly where it is coming from. This involves a bit of calculus and/or geometry, which you may not know, however, your brain knows it, and can work the derivations exceedingly fast if you tell it to.

This is fixed with a simple optical scope. Plus, you cannot use laser sights at night w/o night vision, something easier to equip newer optical scopes with. Optical scopes also give you the advantage having crosshairs, which aid in comensation for movement, wind, or a shoot to kill shot vs. a shoot to subdue. (Do you want to break their leg or hit them between the eyes) If you can't hit something with your eyes alone, or your eyes and a low power scope, then you're going to SOL if something goes wrong with your laser. (Mis-alignment, burnout, breakage)

Then again, i'm also a fan of archery and hand to hand combat.