Some spoilers below.
Episode 3 of 'Last of Us,' to me, was a good stand-alone story. As part of series it did nothing to advance the story, plot, or setting. If it was an episode of Black Mirror, on how a guy with unique skills in a unique situation can survive, find love, thrive, and live a fulfilling life in a post-apocalypse setting, it'd be great. As part of a series? No. You introduce characters, get the people involved and interested in the characters, and then kill them both off. It could've worked if it showed how life in this setting worked outside the QZs for normal people, but a guy with unique skills in a unique situation doesn't do this.
It was a good self-contained story and it really seems (to me) it was only done for one of two reasons - to stretch a ten episode series out to twelve episodes (or some such), or to add a self-contained story into another story specifically as a bone thrown to a specific audience. Either way, it was probably a good financial decision, especially if it got people to talk about the show and made more people aware of it.
My kids said one of these guys was in the game and still alive and part of the story. If I had to guess I'd bet there'll be one other self-contained story like this in season 1, and we'll know for certain if this is stretch material or flag-flying. As long as it's a good story that stands on its own I don't care, because this series is a lot better than what we've been getting lately, and from what my kids say is sticking a lot closer to the source material than most adaptations do. It seems in the last five or so years the writers and directors and everyone involved with an adaptation want to write their own completely separate story having little or nothing to do with the source material besides the name and some flavor.
Anyone here every read the "Cradle" series by Will Wight? I love it. He was doing an interview with other writers and they were talking about adaptations and how it has to change dramatically to fit the medium. But we all know it doesn't. I think 300 and Sin City proved that, and The Watchmen changed in a way most fans didn't mind and thought worked fantastically without destroying the source material. I've never once read a book adaptation of a movie that destroyed the source material, it's always a one-way street.