Comic books must be challenging both for artists and authors. It must be difficult to pack as much meaning as possible into such a small unit of space.
There's trade-offs regardless of the medium, but I think it evens out overall. There's a lot of complications to arranging a bunch of panels to tell a cohesive story in a manner that's pleasing to the eye, but you have more tools at your disposal than straight fiction. But literature lets you tell things more at your own pace without being confined to such strict pacing requirements. Movies let you utilize sound and motion to tell your story, but there are far more variables to control and you're limited to what you can depict on-screen. (ie, if I need a character on the moon with an alien sidekick and a nifty spaceship - I can either just draw one or write about it in a novel - movies require building a set, using CG and other special effects, etc.)
There's a challenge any time you're limited in something, but that's also where a lot of creativity stems from. Working around limitations can provide a lot of motive for creative ways to depict something. With comics, the limited space encourages concise storytelling and making efficient use of every element. Often, that can make for a better story than you'd get if you weren't otherwise constrained.
I can see the interest in that, but I think I'd prefer imagining my own stories for them. Take Sarah for example. What a life, growing up in BOS Talk about Army brat... She talks tough, but maybe she's not as tough as she appears. i actually followed her around for awhile, to see what she would do. I think that's more fun...to try to figure them out using in game resources, then to read about them.
Yeah, with Fallout I'd rather read about something unconnected to events of the games. It's a big world out there, and it's ripe with opportunity. Personally, the whole Vault thing could get a bit cliche - it could be interesting to explore in a novel, but it's just one way of doing things, too.
I'd still be interested in hearing about Lyons' trek across America, but that story could be told as well in DLC, or spin-offs. I think that might work well for a graphic novel, actually - because of the episodic nature of something like that.
Honestly, what I'd be most interested in seeing for Fallout would be an anthology. Gather a group of writers to put out some short stories set in the Wastes. This way it would also be not only about adding some background to the world, but would be primarily interesting in seeing what sort of twists the writers can bring with their own unique visions.