I somewhat agree with you. New Vegas and games similar to it mostly shift the focus of attention on the self, the player. Most of the quests are designed to be completed, as such, by an individual. There's another thing that holds back games like NV and that's the "blank slate". The main character doesn't share any history with the characters or the struggles they face so it becomes impersonal quick (fanfiction and headcanon not withstanding). That doesn't mean it can stay impersonal, however.
With time, the player can get involved. What could be, let's say, an ordinary quest where you kill an entire bandit hideout, complete with a "boss", becomes something personal for the main when he has someone else in tow. They encouraged making bonds with NPCs via the companion wheel, added dialogue and questing elements. The "same lines over and over again" doesn't bother me, considering how JRPGs and story-focused WRPGs are sometimes guilty of that. For all sandbox games have against them in the story department, I believe they can use loopholes and different tactics to circumvent most of them, if given enough time and practice.
I don't see it this way at all -- Sandbox games like New Vegas always feel too impersonal with its inhabitants of 1's & 0's, plus the non-linearity breaks the sense of flow where I just stop caring and won't continue playing. This is what the Elder Scrolls game did too. New Vegas was a bit better because the writing of Obsidian kept it interesting, with the occasional interesting characters, like that one Major voiced by Kris Kristofferson or Cass.
Chris Avellone has made this opinion of his clear repeated times before.. Here's one such case.
Another example would be his appearance at PAX East along with Gaider & Ken Levine discussing Plot & Play.
Avellone argues that the best story is created by the player using the systems and tools placed into their disposal by the designer, as opposed to crafting a scripted scenario, you'd litterally create your own "ultimately let the systems and the player's interaction with those actually create their own story. The main example was namely, New Vegas.
"One particular example that comes to mind is .. Josh Sawyer, who was playing through Fallout New Vegas for the second time. And he decided to ****** off both factions in the game, who hate each other. And when you ****** off either faction in the game, assassins will attack you, which is pretty typical for showing reputation mechanics in games.
But because he had chosen to ****** off both factions, which is something we hadn't accounted for, he woke up in the Mojave Wasteland one morning to find that both assassin squads had spawned in but rather than attack him, they launched at each other, murdered each other, and Josh just went by, whistled, looted all their corpses... And I could have spent like a month and a half trying to do a narrative design solution that would set up that situation, but because of the mechanics Josh was able to have a story all his own because of his actions in the environment." ~ Chris Avellone