Much of that (crystal gate, shard of evil) is unrelated to the vale, and more the assumed cosmology of all worlds. The tiefling vs dragonborn war is neat but pretty much just a name; there is literally no details or date. Again, Keep on the Borderlands or even Red Hand of Doom was as much a "setting". All the lore on Nerath/Nentir could fill a 32-page book. It's not a setting, it's a location with backstory.
I think its a bit more complicated than that, and that has everything to do with 4e's "one mythology" system.
Nentir Vale on its own is just a micro-setting. A couple of cities, dungeons, some wilderness, etc. In a certain regard, its no different than the Elsir Vale, the Valley of Obelisks, or Thunder Rift. On its own, it'd be nothing special beyond those settings.
However, most people also tack onto it the whole Dawn War mythology that is prevalent in the game, mostly due to their co-introduction and that Nentir relies heavily on it for its backstory. So the Astral Sea cosmology (which was supposed to be 4e universal, considering how they retconned both Faerun's and Eberron's cosmologies), the primordial/gods backstory (also later retconned into Faerun), and several of the "ancient history" elements of the world (tiefling/dragonborn wars, Nerath, etc) got associated with Nentir Vale, making it seem far more world-like than say Thunder Rift or Elsir Vale (in 3e) did.
I'm sure that if 4e had been more successful, another round of adventures or a different Dungeon AP would have fleshed out another corner of the world, using much of the Dawn War mythology and history but ignoring Nentir as the home base location. In time, the "World of D&D" would have formed and Nentir would have been no bigger a part of it than Karameikos is to the Known World or the Dalelands is to Faerun.
That said, I think when most people want "Nentir Vale" as a setting, they also want the Dawn War Mythos, the expanded map ideas, the Astral Sea cosmology, and most of the default 4e "core" concepts (racial origins, etc) solidified into a setting on par with Realms, Dragonlance, or Eberron. In essence, boil 4e's default fluff down into a single setting that for lack of a better name is associated with the default starting location in the DMG.