Anyways, on the topic.
It wouldn't be very realistic the actually have a flamethrower in Liberty City now would it ?
Same goes for the chainsaw, Not much trees to cut down is there ?
As for the Machine guns, I mean its okay to carry a M60E4 in COD4, but could you picture Niko having one ?
Seriously, calm down its just a video game. Its not your life there pal.