W:ET and RTCW take place during WWII, and they uses real world weapons - yet they play like a twitch shooters, with no ADS or recoil.
Brink does not use real guns. It may use real world weapons as inspiration, but the guns in Brink are fictional. Part of the reason in doing this, is so they can give the weapons the attributes that work best, which isn't necessarily the stats of their real world counterparts.
The Heavy's minigun in TF2 does just that, as does the Venom in RTCW. Saying no one can relate to weapons that behave different from real life, because they don't have access to them in real life, is a bit of a stretch.
As long as the weapons feel and sound powerful, players will feel immersed, regardless of their stats or handling mechanics.
For starters, RTCW was released in 2001. Red Orchestra pioneered 3d iron sights, and thus ADS, in
2006. ET:QW was released 2007, and features ADS.
Secondly, there have been many, many FPS where real world guns have been used but "
not quite". Typically this is not due to "oh, there's just not enough interesting gun variants out there, so we'll make our own", but rather the fact that licensing all of these guns can be a major pain in the rear. Take the Specter SMG in COD:BlOps. Anyone here who plays the game should be familiar with it. Do you remember a gun called the http://goldeneye.wikia.com/wiki/Phantom in Goldeneye? Looks familiar doesn't it? If a developer truly wants a gun with properties completely unique to their imagination, they make their own guns. Again, we can look back to UT3. Shotguns?
PFFT! I say! Flak guns is where it's at! When you use real world weapons, even if you don't use real world names, you are already taking steps to approach reality. It makes no sense to include realistic visuals alongside completely unrealistic game mechanics. Brink incorporates semi-realistic visuals, and thus should be at least semi-realistic in play. It just, makes, sense.
The comment about the heavy's minigun, and indeed the prior comment about mounted machine guns which I skipped over for the silliness of the statement, are bizarre comments to say the least. While yes, they effectively are damage spewers.. Real world miniguns are actually highly accurate due to the weight of the system, and the seperate chambers from which the rounds are fired. Nobody puts ironsights on miniguns because raising them to your shoulder just isn't practical. But that's why they have tracer rounds every so many cartridges. That way you can lead the gun to your target with sustained fire, since the kick is negligable (again, due primarily to the weight of the system far and away making up for the kick imparted by the comparably tiny rounds). The comment with mounted machine guns is a joke, because what are these LMGs mounted to? My heavy's arms? I'm sorry, but that's just not as sturdy as the back of a truck. When you dampen physics, people can adapt fairly readily because it's still something familiar to them. But when you change physics entirely from what they understand in the back of their head, their brain is going to be constantly fighting with it trying to make sense of it. Doesn't mean it can't be hilarious fun, it just means that their brain won't, typically speaking, immerse itself in the game environment, because it's constantly reminded it's a game.
As long as the guns feel and sound powerful, the players will feel like they are firing powerful weapons. But how a gun handles (eg, recoil, accuracy, fire rate, how fast people die), is the biggest component in how a gun feels. As long as that's approaching a realistic, believable state, like everything else in Brink, then it won't detract from the setting or break immersion.