I'd say that, because they only copy-paste plot and shit from the previous games without even bothering to re-enact the depth and importance of it, they are complete strangers to the series. I mean, look at the GECK in Fallout 2 vs. in Fallout 3. It went from this really valuable piece of pre-War tech meant to help the generation from the Old World to survive in the New World, to this piece of junk scrambled for parts to be used in a purifier that's arguably useless considering how everybody managed to get by just fine with whatever water they could get, and that's not to mention the fact it's been 200 years since the Great War. In Fallout 1, water-urgency plot really means something since we were given a time limit, and there's a tension among the Vault 13's dweller regarding whatever water left before it finally runs out, while in Fallout 3 it seemed only James is really concerned, while the rest around him doesn't even give a fuck except water beggar but he's alone and most probably meant to be abused for Good karma.