People who think "loneliness in games" is a bad thing don't get that games are a retreat, an area to relax.
For them, there needs to be constant action, games are entertainment-dynomite, exploding in your face every minute that you play.
Adrenalin-fueled FPS sessions and tense MMORPG raids are a valid way to experience a game.
I guess, after such events, the "everything needs a co-op mode"-people just leave their computer to be alone and relax in the real world while reading a book.
Well, sorry that my lifestyle is not the exact same as theirs.
I like the loneliness in games. It gives me time to immerse myself into a well-constructed virtual environment, enjoying it in ways that I couldn't if I had the constant worry that some Steam-pal simply joined my quiet world.
I want to be alone sometimes in games! The sensory-deprevation tank was an apt analogy for something that I have found: Loneliness is stress-free and safe. You can't fuck up with no-one around, or at least it doesn't matter that much.
Certain parts of your brain can shut off and relax when you're alone, giving you the capacity to deal with your gaming experience more deeply.
I can handle it when someone tells me to stop talking to the NPCs and to stop gawking at the nice environment in an MMORPG because that is not the main point of an MMORPG. However, games like Skyrim have environment, NPCs, basically their atmosphere as the main attraction. The immersion is the entire point!
That just doesn't happen when you're dragged around by one of your friends, who wants to speedrun every quest and who gets annoyed when you stop to smell the roses.