Adding lights to firearms is just silly to me; like tracer rounds and IR illuminators, there's nothing like announcing your position. 'Just another reason to waste money.
Understanding that this is an old thread I feel compelled to reply if for no other reason than to refute this guys ignorance. I take issue with the entire reply, but the quoted part especially. I was a combat medic for a while attached to infantry. We loaded our magazines with a tracer round as the 15th and final 3 rounds in each mag. This allowed us to know in the heat of battle how low our mags were, and frankly once you're 15 rounds into a firefight the element of surprise is long gone.
IR illuminators have a place too if you're equipped for it. I don't see much practical use for civilians, but if Joe Smo has the money to buy a night vision optic and an IR weapon light/laser then how is this not ideal for a bump in the night scenario? People generally don't run this configuration because it's cost prohibitive, not because it's ineffective.
IMO weapon lights are crucial kit for any build. Target identification is a must, full stop. If you are shooting a firearm at night without knowing for sure who or what that round is going into then you don't need to be owning firearms. If you don't want to be broadcasting your position with a weapon light constantly on, then that's why the Good Lord allowed for the creation remote switches. Light up your target, identify it, then light up your target,
in that exact order.
When it comes to weapon lights there's also the disorientation factor. There's something to be said for blinding your target with a high lumen light. Alternatively, strobing lights provide you the nearly all the benefits of a traditional light, but they can REALLY jack up a targets ability to engage you.
We can talk about "wasting money" but waste is a relative word here, and just because some people are cheap doesn't mean there aren't benefits, and in some cases crucial benefits, to outfitting builds with certain kit.