The issue with lazers I feel is that its easy to say you wont aim at the face. But when someone peeks a corner at you, and the only thing you can shoot at is their face, what do you do? not shoot? Because everyone, me included would instinctively fire off a few rounds at said peaking individual. With a lazer on... Well, then you have just risked giving them eye damage, all be it unintentionally. Happened to me at a Gaol night game with a guy running a green lazer, didnt get me in the eye, but was all over my face when I peeked the corner.
In gameplay there are ample situations from lack of alternative targets to random muzzle sweeps that can make the best intentioned player inadvertantly lazer an iris.
Quietly I have always been suprised when I have found sites that allow lazers. But I also know of many that dont.