i think there's two factors at play.
1) this gen is just starting... sure the consoles have a few years on them now but the past year is really when we started to get to the meat of it. in the meantime we've primarily gotten cross gen titles or re-masters. even MGS5, one of the headline graphical showcases, was cross-gen. we're just now getting out of the woods in terms of "current gen" being standard. then you factor in that fallout has been in development for about half a decade now, this becomes more relevant
2) this gen simply isn't that big of a leap, and it's just something we'll have to come to terms with. if your PC has a 660 and an i3 processor, you're about in the same neighborhood as a ps4, which says a lot. the reason why Oblivion was "lifelike graphics" ten years ago was because the console tech situation was the inverse of what it is now, a fairly massive leap. bethesda didn't have to scale lower, or in a worst case scenario, release a total gimped port or no port at all (in which an AAA PC exclusive wouldn't fly at all these days)
it's something to keep in mind... and before somebody brings up witcher 3, it's already been discussed ad nauseam why the two games are hardly comparable. hopefully by the time elder scrolls 6 (or maybe, fingers crossed, Obsidians new Fallout) hits there'll be a solution where a massive open world won't compromise the visuals, remember skyrim was leaps and bounds over oblivion. but we're not quite there yet.