I know you're being ironic, but I enjoy breaking strawman arguments in order to show the dominance of the original games over the newer ones.
creme of the crop aspects of other titles in such a seamless way it blended right into the Fallout universe & lore.
Jet being pre-war, Ghouls no longer needing to eat/drink despite Necropolis, Gecko and Reppcon HQ saying otherwise, and Potatoes being extinct blended right in with the Fallout Universe and Lore did it?
Fallout 4 moves in a brave new direction while keeping up with modern times.
Fallout 4 could have easily kept up with modern times, while at the same time having a decent dialogue system, out of combat skill checks, and accurate lore. These are aspects that they didn't have to ditch, but did so.
There are no strict set of rules that a Fallout game should abide by in order to be a "true" or "proper" Fallout game
Yes there are. It has to have the ability to define your character, consequences for actions, and opportunities for non-combat centric characters. Fallout 4 fails in these basic aspects.
the aspects of Fallout that are most enjoyable for the true fans
And we're not true fans?, If anything we are truer fans than the Bethesda fans, because we like the series for what it is, not for what is's become.
this is nothing new and if it had not happened we'd all still be playing stale turn-based isometric RPGs.
Some people(Including me), Would be happy with that.
The reason Fallout 4 was such an outstanding success in comparison to the lesser known 1 and 2 is because it actually tried breaking new grounds. I know this is not the popular opinion here but it has to be said.
If you looked at User Reviews, or Steam Reviews, you'd see it got more hate than any other Fallout game ever made. Not to mention that the only reason it's "An outstanding success" is because the vast majority of people are casual gamers who like to shoot stuff, and aren't really in to Roleplaying, also most people are too dumb to realize that older games can be good, and automatically assume old = outdated. Not to mention that Bethesda had one of the biggest marketing campaigns out of any game, so the vast majority of FO4's fans are people who never played another Fallout game.