In my personal opinion as one of the newer generation people, it's because New Vegas is arguably the best game in the series. I started off with 3 in 2010, and hopped to New Vegas several months later to see why many people liked it more. After I got through the meh first part of the game where many Bethesda fans stopped, the game was just absolutely amazing.
Not really. There are many factors as to why New Vegas was held back badly compared to its predecessors. I would point out that [1.] the shit engine and shit overall gameplay mechanics that's inherited from Fallout 3, and [2.] the fact that the transition from Fallout 1 and 2's top-down isometric-oriented gameplay to 1st and 3rd person still couldn't compensate fpr the freeform interactivity that allows vast player agency and freedom on how to play the game that existed in the predecessors are the main reasons why. (I've already talked about what I meant with freeform interactivity few posts above) Mind you, I was just like you, as in I started the series with Fallout 3, and it was pretty late in 2015, and still I highly preferred the gameplay of Fallout 1 and 2.
Having said that, when it comes to quest design, narrative design, and overall story and lore, and how it provide content in regards to character's stats and skills, New Vegas is a worthy successor to the originals, and even surpassed Fallout 2 in regards of keeping the spirit of Fallout 1.
Then a couple years later I tried Fallout 1. I can attest that the barrier of entry is pretty high. After a couple years of ditched attempts to play the game, I finally did. I'm not sure I can say it was worth it because the game didn't age very well, and honestly I didn't have much fun until the very end of the game where everything I built my character up to do paid off and I cheesed the game to kill the master without too much problem. The only memorable things to me about that game are the concepts it laid out and the final boss.
What do you mean with it not aging very well? Is it that it doesn't run very well in your computer, or is that there are better turn-based RPGs out there, particularly when compared to RPGs of this day and age? Because if it's the latter, then I agree with you; Age of Decadence and Underrail are both cRPGs released in 2015 that has much, much better turn-based combat gameplay mechanics compared to Fallout 1 and 2.
However, the fact that Fallout has that freeform interactivity, and up until now there are no RPGs at all that even try to replicate that gameplay features, I still pretty much preferred to replay Fallout 1 and 2, especially its TC mods like Fallout 1.5: Resurrection and Fallout of Nevada, over and over again.
I can almost say the opposite of 2. While the first part of that game is a total fucking slog, it gets really good after Modoc assuming you didn't travel to Redding first. Most areas are actually interesting. Many of the companions actually feel like more than a recruit-able ally. They threw in a lot of silly humor to make the game not as depressing as the first one, but at the same time they put in things that were even darker than what was in 1. They added background noises that bring life to a dying world. Once you actually have a gun that's not total fucking garbage, then the game gets good.
If you think this is all good, it's on the contrary fpr me. I think that they should've kept the spirit of Fallout 1's extreme focus on the tone, atmosphere, and execution. Fallout 2 felt like there were a lot of disconnection between one content and another. Not as bad as Bethesda's Fallouts, but still.... and the fact that the game wasn't as focused as Fallout 1 was attributed to the fact that the development of the game wasn't as coherent as when they developed Fallout 1. This was confirmed by Chris Avellone at RPG Codex, btw, and you can even look up that Tim Cain, Leonard Boyarsky, and Jason Anderson, who were the main heads of Fallout 1's development, all left halfway through the development of Fallout 2.
However, everything it did, New Vegas did better in my eyes, regardless of how incomplete the game was. Where in Fallout 2 can you get the same experience as talking to Caesar, or getting close to Boone, Arcade, Cass, or Raul? The choices you make in the game are even greater, and honestly the dialogue options are one of the most important things about that game to me. 2 doesn't have the same level of choice making.
Well, Sergeant Arch Dornan as mentioned by Carmelita Fox above? Also, First Citizen Lynette, Marcus, Sulik, Myron, that scientist guy or whoever at the Oil Rig with whom you can have discussion with whether or not it's morally acceptable to just wipe out the entire population of wastelander. I don't think it's right to compare 2 and NV in this regard, however, because 2 literally have less talking heads than 1, despite the fact that 2 is literally the bigger game. You can say that the thing about New Vegas is that every NPCs have talking heads, but I will point out that since the game has full voice acting, it also means the text count has to be drastically reduced so it can be accommodated within the reasonable budget provided.
And I disagree that 2 have less choice making. Have you tried replaying Fallout 2? Because the thing about 1 and 2, is that they don't show you stats and skills checks in dialogue, UNLESS you reached the threshold, or close to it. Meanwhile, New Vegas immediately showed you ALL of the possible stats and skills checks, which gives the impression that the choice in this game is 'even greater'. Granted, the game also changes the failed checks line, I think it's a mistake in their part to just show you every possible dialogue checks you can attempt in this game.
I believe this, because I honestly believe that when Bethesda made 3, they took most of their inspiration from Fallout 1. When Obsidian made New Vegas, I believe they took most inspiration from 2. The New Vegas and 2 are very similar in many ways, and I believe that Fallout 2 is the easiest of the original 2 games to play if you liked New Vegas.
That is an interesting theory, but a weak one, I'd say. Bethesda wasn't 'inspired' by Fallout 1, nor did they took most of it from Fallout 1. What they did is a complete rehashing of the first two games, because as you can see, all the elements across the originals were there. Water 'problems', FEV, Super Mutants, Armored Vault Jumpsuit, The Brotherhood of Steel, The Enclave, The GECK, Harold, Jets, etc etc.
Meanwhile, Obsidian may seems like they took most of the inspiration from Fallout 2, because it's obviously the game they are making a sequel for. Obviously the new elements like the NCR will be present at large here, coupled with what remains of the Enclave, since New Vegas takes place directly at the timeline
after Fallout 2. And I also wouldn't agree to the notion that New Vegas and 2 are similar in many ways. Sure, it has New Vegas that can be compared to New Reno, but it doesn't for example, have shit tons of pop-culture references and Easter Eggs that's present in the majority of Fallout 2's content, and there were much less wacky stuff like talking deathclaws, aliens, and ghost in New Vegas, so in that regard New Vegas was actually a much better sequel to Fallout 1 in keeping itself focused and coherent, through and through.
And yeah, I agree that Fallout 2 is the easiest of the originals to play. There are a lot of QoL improvements it brings to the table, and many people would agree with you as evidenced by the fact that most of TC mods for the originals were made using Fallout 2's template instead of 1's. But I'd say you missed ALOT if you skip Fallout 1. How the game setup it's tone and atmosphere all the way from playing Maybe by the Ink Spots when you first launch it, and all the way to the confrontation with the Overseer, and finally the Vault Dweller's back turned to us as he walk away to the tune of Maybe playing once more.... it was one of my most favorite gaming moments of all time. Considering 1 is relatively much shorter than 2, it could've been a much more replayable game, if not for the fact that a lot of QoL improvements of 2 were missing in it.