No idea. It's why I always scratch my head at the 3D haters who complain about "dark screens". I don't even have a 3D Vision 2 monitor, but in 3D mode the thing goes into torch mode and I've never had to adjust the in-game brightness for any game that has a utility. I guess some people just are used to everything glowing.
Some people does this when the game is too dark, even when it's suppose to, like survival horror. I've seen people who does previews and such do this for games that purposely limit your vision at night.
I used to game on a super old HDTV. Like so old it didn't even have HDMI ports. Over the years it gradually got darker and darker to the point that all of my games had to be on max brightness just to look playable. So I guess I was one of those guys. Also I find in some horror games they love to put the brightness so low that the game becomes frustrating. I get that horror games need darkness for mood and all that but back when I used to play those games at the recommended brightness I would miss key items because I just couldn't see them.
Aside from that though I never turn up the brightness because it usually makes the colors look worse
Let me tell you why, sonny! You whippersnappers don't know about the good ol days.
You see, in the 1990s games, first person shooters specifically, used to have very little in the way of lighting. So a game like quake would have some lighting effects but it was mostly done with texture work. So if you were playing online you had to jack the brightness to the max to see in dark hallways and whatnot. If you didn't do that you would get murdered.
I'm assuming that people still do it out of habit. I know I always kick it up a few notches even though it doesn't have the same effect anymore.
I tend to turn the brightness down in most games. It seems like, by default, most games seem to have a washed-out look with default settings. It really benefits games like Fallout Vegas and Metro 2033. Far Cry 3 is another one.
Damn, I was wondering why when you're asked to set up the brightness, I always have to crank it up in game to see the logo. I didn't realize I was better off just brightening the TV, although it seems kinda obvious now.
I really love RE6, and usually hate dialing up brightness, but yeah, that game practically requires it. I suppose if you had a very particular set you could play it at default brightness. Doesn't help that their brightness check is set against a bright background instead of the usual "recede into shadows," lol.