Well, Fallout 3 and NV also probably have more "named" item treasures because, as "modern"/sci-fi games, they can't really fit in a wide variety of Magic Powers to give equipment. There's AK-47 and Named AK-47.... but not AK-47 of . At least not if they want it to be even vaguely "realistic" (Versus, say, Borderlands with it's fire/shock/acid guns of infinite ammo)
FONV gave you the chance to do a little bit of "enchanting" with the weapon mods. But even that was pretty tightly controlled. Item creation just isn't quite as free-wheeling as it can be in a magic-rich fantasy setting.
New Vegas played so differently from Elder Scrolls and Fallout 3, I'm not even sure exploration could be argued as a mechanic within that game. I felt that the experience was a lot more directed than even Fallout 3. From enemy placement, to quest progression, it always seemed like the game had one very specific location it wanted me to go at any given time. It played a lot more like... Mass Effect 2 I guess. Where you're intentionally directed along the main narrative, but there's lots of other side missions to do along the way. That interpretation is optional as per the design of New Vegas, but not adhering to that path always seemed... wrong.
Playing a ton of hours (And I mean a ton) in New Vegas gave me an appreciation for just how different Bethesda's games really are. Here is a game that runs more-or-less on the same tools Bethesda made for a game that was essentially a prequel in the classic sense of videogame sequalage, yet they feel fundamentally different in how they approach the role of the player.
Compare say... Wasteland Survival Guide, arguably one of the first quests the player will receive in Fallout 3, to... Really any quest in New Vegas. WSG plays out almost like an entirely different faction of the game, taking the player, quite literally, all over the map before its final resolution. Considering that WSG is acquired in the first major town, from the shop (likely the first place a seasoned RPG player will visit) and the fundamental difference in design approach is pretty apparent. I'm actually having a really hard time putting the feeling into words.
I guess in a bit of a cryptic manner, The player exists because of Fallout 3, where as Fallout: New Vegas exists because of the player.
With Oblivion and Skyrim though, you see a lot more of that trending where the World revolves around the player, and the world tries to fit the player. Instead of Fallout 3/Morrowind, the player inhabits the world, and tries to find his place in it. The dichotomy isn't something that's superficial though, it's buried very deep in the design, but at the end of the day, I feel that when the experience revolves around the player, you have a hard time convincing that very same player of the world's integrity and believability.