In Into Thin Air, bottled oxygen represents the way that technology makes climbing Mount Everest a much easier proposition. The only question is whether this is a good thing.
First we have the pro-O2 camp. Although "relying on bottled oxygen […] is a practice that's sparked acrimonious debate ever since […] 1921" (11.28), these folks will tell you (rightfully, we might add) that the first ascent of the mountain in 1953 would have been impossible if not for the help of good old O2. In this perspective, bottled oxygen is just another tool in a climber's repertoire; it's simply a means to an end.
Then we have the die-hard purists. This bunch looks to Reinhold Messner and Peter Habeler for inspiration: Messner and Habeler reached the top of Everest without bottled oxygen in 1978, which was "hailed by climbers in some circles as the first true ascent of Everest" (11.30). These purists argue that bottled oxygen only encourages lesser-skilled climbers to take a shot at Everest, which makes things more dangerous for everyone.
It's kind of hard to argue with that perspective given the events of Into Thin Air. Even Krakauer lends credence to the idea, suggesting "the simplest way to reduce future carnage would be to ban bottled oxygen except for emergency medical use" (21.28). On the other hand, there are plenty of climbers in the book (Krakauer included) who climb both responsibly and skillfully, despite using bottled oxygen.
Which leaves us with one question: What do you think?