But no one wants what our brain "sees".
Yes they do, and so do you. What your brain "sees" is all you know. You will never be able to know what our eyes "see" without brain procession.
How can you not understand this? As far as you know, everything in life is dyed in a pink filter and then our brain removes that. it's impossible to know what someone else sees. If when you look at green, you see the colour that everyone else in the world calls red, you wouldn't know it. because you would have been thought that that colour is red. You would be calling it red since you were a child, and no one else around you would be able to realise that the "colour" your brain "sees" is different.
Next, you said:
Everyone here is complaining about depth of field and motion blur being added to games when they're effects we always experience.
Motion blur in games sucks, and it's unnecessary because, like you said, our eyes already have it. If I look at something in my desk, things closer than it or farther away from it, or in the corners of my eyes and unfocused.
But this effect isn't turned off when I look at a screen. If I'm looking at the centre of the screen, the sides are not focused. If I look at a corner, the centre is not focused.
There is no reason to add depth of field, you already have it. There is only disadvantage. Because you can LOOK with your real eyes to somewhere that the in-game character is not looking, and so what you are looking at is not focused.
Your character can look forward, and you can look at a corner of the monitor and see everything blured. You use the mouse to change where the character looks, not your eyes. So it's stupid. If the game "tracked" your eyes, and changed the blur as you moved.... then it would be stupid too because it would just be adding blur to your natural blur. You wouldn't notice it. Because wherever you look will be focused.
If I explained myself well and you understood this, now you can realise that if you can notice the blur then it's already failing, it's ruining your view and experience. in real life when you look at something directly it's not blured. It's the exact opposite of realism.