Calling Fallout 3 illogical yet overlooking some of the absurdly gaping plot holes in Fallout 1 and 2 is also a little silly. They've all got their storyline quirks, it's part of the charm.
What absurdly gaping plot holes? Seriously, I've never noticed any plot holes as large or absurd in the previous two games as those that are found in Fallout 3.
Fallout 2 was a great game, but the sense of immersion it gave me was nowhere near as powerful as Fallout 3's, and in the end that's what truly matters in my eyes. Fallout 3 made me part of the world; I'd sit on a rock and watch Fellout sunrises, and wander through the DC ruins just to explore them. I'd parkour around Megaton while listening to its music, go in and take a seat in Moriarty's and watch the flow of townspeople, wander through the spartan barracks of the Citadel and Fort Independence, and gaze at the shattered majesty of the Capitol and the Mall. FO2 couldn't offer immersion to that degree for me, and the locales of NV didn't resonate with me quite as much as the Capital Wasteland.
It's interesting that you mention this, and I'm not saying you're wrong I'm just going to present my stance on immersion because it's the exact opposite of yours. To me, immersion lies in how the game world is written. I don't find NPC behaviors or graphics all that important because these aspects are just abstractions of what's really there in the first place. I care more about the writing of the world, the writing is what immerses me because the writing is not an abstraction, the writing is what really happens within the context of the setting.
If the writing is horrible I just can't be immersed in the game world... it doesn't matter how pretty it is, or how detailed the NPC behavior is. Those things are meaningless if the writing of the world is so ridiculous it feels more like Alice in Wonderland than something I could see as at least somewhat believable. My problem with Fallout 3 is that the game world felt like Alice in Wonderland, a bunch of nonsensical places and events that are there for the wow factor, and aren't given any sort of rational explanation within the context of the setting.