First off, there is no noticeable input lag from the placement of the crosshair on the screen, a whole frame is displayed way too fast for there to be any sort of "disadvantage" to those playing with a lowered crosshair. I guarantee you that any difference you think you're noticing is either something else causing lag (of which there are many in Reach atm), or just a placebo.



Secondly, on console everyone has lowered crosshairs, so it wouldn't make a difference because as there is no crossplay between console and PC.



Thirdly, the animations, maps, and art are all built around a lowered crosshair, changing it makes the game look and play worse. Bungie put a lot of work into designing maps and skyboxes to work with the exact camera settings that were used in the original version of Reach, lowered corsshairs included.



Fourthly, having centred crosshairs actually gives players a disadvantage because they actually see less on the screen, considering you have to look further down when aiming with centred corsshairs and that means you can't see 20% of what everyone else can see. This is especially important considering that most games now start with headshot weapons, and therefore the ability to see more of the map is vital. Even if it were true that having lowered crosshairs caused noticeable input lag, this is a much larger disadvantage in my opinion.



The only reason 343 decided to allow PC players to raise the crosshairs is because they would complain otherwise, almost nobody on console cares or even notices, so why mess up the game when there aren't people pressuring you to?