It is because the graphics and enviroments and story are more realistic. They are not cartoony art style or an over the top premise for the story it is something people can feel for and relate to why the resistance is doing what they are or vice verse why the security is doing what they are. Sure there are unsrealistic aspects just like any game if your going to try and twist it like that no game has a realistic feel otherwise you wouldnt come back when you die, you couldnt turn into the enemy, soldier couldnt attach themselves and take dmg for friendlies, engineers couldnt make turrets pop up out of thin air, couldnt crap ammo, couldnt get shot more than once, and a class base system in games would be non existance everyone would have the standard issue weapons and would sit around camping.
First off, the artstyle is a bit cartoony, It reminds me of caricatures, and second, you are arguing every single aspect of game to justify you point. You are basically taking every single aspect of every game, comparing it real life and saying, see no game is real. I am just talking about the very basic game mechanics of Brink, not the fine details. Like if someone totally new to the game, jumped in. The last thing on their mind would be, "wow! this game is so much more realistic than other shooters!"
I beg to differ because you cannot have all weapons with the same stats and movement speed the same when body types have different healths otherwise things become unbalanced and you put emphasis on what body type people choose and there would be no reason to play as any other body type than the one with the most health since everyone would take the same amount of dmg because everything is equal and they all had the same movement speed.
You can argue that different body types aren't equal, so weapon movement doesn't have to be equal, but you would be wrong. It isn't as simpe as "you have more health, so you have an advantage." The differences in health and mobility between the body types balance each other out - Heavies may have more health, but they are bigger and slower (easier targets). The same is true for Lights - they may have less health, but they are smaller and more mobile (harder targets). That only leaves weapons, and the weapons need to act as the constant in the equation.
More or less, all weapons within a category behave similar. Long range rifles have high damage, low ROF, shotguns are good close up, and SMG's and rifles (this would include miniguns, since essentially, they are just huge rifles with big magazines) all behave similar as well. I'm not talking about in real life, all talking about according to the current stats.
So if my health and your mobility counteract each other, but you have a gun has faster movement than mine, now you clearly have an advantage over me, that is not skill related. It has nothing to do with me wanting to play Heavy, it has to do with the overall balance of the weapons, and turning a key benefit of a body type, into a handicap.
As I stated above it has nothing to do with the heavy class its a penalty for the burden of carrying such heavy equipment like I said if anyone could equip them I would suggest the same thing. If you will be an unstoppable tank regardless slightly slowing down your turn controls while having heavy weapons equipped should not be an issue because you will adjust if you know how to play the role.
It's a poor argument you propose here. First off, and my original point, turning a key benefit of the Heavy body into a burden, is totally counterproductive, and once playing one's role involves having to practically avoid it's key weapons, not to compliment the situation, but because they have a clear disadvantage that no other weapon has, and practically no bonus to make up for it, the body type is broken and that weapon is pretty much rendered useless.
IF they had a slower tuning speed, I would expect it to be compensated by something substantial, like high damage, not simply because "they're heavy." As the stats are now, they do not have high damage, or really high anything, compared to other weapons, other than magazine size.