Not a lotta "yes" folks giving reasons, so I'll post mine as I voted: Yes, keep the option to display the reticle.
I'll be fine either way, and given the amount of people that seem to have difficulty separating IC from OOC, I can see why "No" would be a popular answer with such a large community, I just wish it weren't.
First, there's already the option to remove the reticle... so I can't see any argument about one's own immersion being relevant, as the ability to turn it off is there. It seems the argument is more about players forgetting that their character might not be a skilled shooter, and removing the reticle will "force" them to keep that in mind.
For me, if a player is given resources, they always have the choice whether to introduce those resources into their character. A player with shooting skills can easily play both sides; they can be a marksman, or they can play a lousy shot, purposefully missing. However, removing the reticle biases characters who have skilled players, as it places a burden on an unskilled player wanting to play a skilled gunman. Is it a big deal? No, but that's my rationale.
Really the only reason I can see to forcibly remove the reticle is the thinking that there are too many folks who'd use it inappropriately (probably without thinking or realizing it) to inflate the skill of a character. And I get it, it's a great & valid reason, and "the reticle removers" group is probably right. It just saddens me to see that we have to restrict players' freedoms because we can't trust each other. But I'm admittedly new to the massively-multiplayer roleplaying community (massive as compared to my history of RP'ing in groups of 4-8 folks where everyone knows everyone)... so I'm probably a bit naive about it.
Anyway, my thinking would be leave the option, allow players choice, and remind other community members about the merits of immersion without it as well as reminding folks that their character probably misses a lot more than they as a player do.