All I'm getting out of this thread as that a lot of people really don't understand how real lasers work. Considering this thread is titled with 'realism' in it, I find that extremely baffling.
Correct, we do not currently have legitimate weaponized lasers (though some people have made some really powerful ones on Youtube) and so there is a certain amount of suspension of disbelief required to use them in a game. But the technology is real and theoretically possible to make real weapons with them based on that tech. Did you know that a common laser pointer has an effective blinding range of almost 50 feet, and can be SEEN up to 2.2 miles? That's just a rinky-dink little keychain laser pointer. A 500mw (half a watt) laser can do serious damage at over 500 feet, and can be seen up to 22 miles away. That's HALF a watt. Imagine one powerful enough to be used as a weapon. Something say around 5 watts. That would probably be strong enough at 50 feet to punch a hole in solid steel with little effort. Games seriously downplay the power of a laser weapon, mostly for balance purposes, but sometimes because they didn't bother doing any research on the subject.
My point is, a laser weapon strong enough to deal actual damage to something just be being hit with it is not going to lose any effectiveness on a map the size of the ones ingame.
If you want something that loses effective damage over range, look no further than plasma weapons. Deadly up close, useless at range.