what is feature in video games that is no real need for it, but you who'd like to have anyways.

reload.. its a video game, so it's not really needed, but it adds to the realism. xD

option to turn individual HUD elements off

Cutscene-only mode, especially for story/cutscene heavy games (typically RPGs).
Maybe unlocking only after you finished the game, and in case of branching paths only unlocking the paths you've played through.

But sometimes it's just nice to replay the movies for the plot, without having to go through the game again.

Quicksave.. you could just save from the menu, but it is convenient to quicksave

Exit to Windows

I mean, it's not really needed since you can alt+f4 out, but if you want to do it ~legit I don't like having to go through multiple menus. The worst I've seen was the first Ass Creed where you had to go through like 5 menus, some of which involved loading and animations and what not.

Modding. Even mediocre games can be turned into a masterpiece with the ability to mod. As others have said, stuff like autosave/quicksave and turning off hud elements for screenshots and so on are great to have too.

The ability to choose voice language, menu language and text language independently from each other.
Some games allow it and I honestly don't see a reason why would a dev omit it (other than it requiring extra work, but AAAs have no excuse).

General dialoge subtitles!

i have a hard time understanding spoken english so having subtitles for all dialoge, specially from npcs nearby, helps a lot!

Having an option to choose the subtitle's size. I like to hear the original voice acting in some games, but their subtitles are usually small. Telltale does this and it's a nice option to have

Quick saves. Seem to be a lost art. Silent Hill 3 on PC showed us that the excuse of "the game mechanics cannot allow it" was pure bullshit.
Key rebinding. Ditto. (Not everyone worships the WASD system, and I'm not even a leftie or using an AZERTY keyboard to be even more frustrating.) Added bonus if more than 12 keys could be used and we don't have an option like "Use/Sprint/Cover/Heal = Space". (Coincidentally, I still want the person who designed the Mass Effect 2-3 control scheme to be publicly tortured and executed.)
Configuration files. Ditto again.
Non-linear maps/levels/world/game in 3D action games. (All hail id Software. Never though I'd ever actually say that…)
The ability to actually turn off aim assist in a shooter, not just set it to "not that obvious" mode.
Health packs. Anyone remember those before the Era of Wolverine?
An in-game menu option that quits the game. Not exit to the main campaign menu, then exit to the main single-player menu, then exit to the main menu, then exit to the title screen, then exit to desktop. At least Alt-F4 still works in most cases.
HUD customisation.

The ability to set spoken language as different one from subtitle language is feature I'd really love.
Photo mode would be really great as well.
Opening and supporting character models for easier messing around manipulation doesn't really count as feature, but I'd welcome it.

Quick saves, like Talgaby said, plus the key rebinding. But what's the most important thing here is that I should be able to rebind the quick save to one of my side mouse buttons.
As a completionist, I love when there are stats to see how far you've gotten percentage wise. It feels satisfying to see it go up. An even better thing would be a dynamic percentage that would be shown on one of the corners of the screen. Picking up an item or completing an activity and seeing the percentage go up and the game telling you it went up by saying "21.3% (+0.1%)" and the counter adding it to the percentage would be amazing.
It's so weird, but I'd love that :D

Beards for all characters.

I NEED an option to skip any useless, annoying, impossible fight so that I can continue a nice game instead of throwing it away after 20min of gameplay. Really this should be obligatory in any game.

Throwing grenades away from You in fps'es, and option to hide off hud for screenshot and esthetic purposes :3

Color-blind options.
Skip all cutscenes.
Splitscreen co-op

• Quick Saves and Reloads
• Key re-bindings
• Ability to pick Language for Audio, text/ subtitles etc independently of each other.
• HUD optimization options
• Configuration files
• Modding support
• A proper and extensive options menu I suppose all the above points fall under this but for the love of God, so few games have a decent options menu, especially the graphics option. This is why I like WTF..? reviews from Totalbiscuit

On a related note. the photo mod that you mentioned in the op, isn't that a lot like what nVidia ANSEL is supposed to do? I'm not sure but one of my friends was posting some wicked screenshots earlier with ANSEL.

Here is the link : ANSEL

The ability to write notes on the in-game map, like in Ultima Underworld.

Skippable cutscenes.

I hate it when the game doesn't let me skip the cutscene. I do watch all the cutscenes, but I want to skip it if I already watched it. Especially if I load the game several times. Neptunia 1 doesn't have this. We can only increase the dialog speed.

Configurable keys

Especially for the games that requires keyboard.

Steam cloud sync

So I can load my progress on any PC and don't bother with my save files if I uninstall the game or format my PC.