That exactly what they do though? The foundations are broadly the same. You can tell its Doom just by looking at it. Just they all play differently with added mechanics. They might not all work for me personally but I prefer that to just more of the same.
The story can just be easily ignored and skipped in DA, I think I watched one cut scene.
2016 is the most "Doom" game for me, they nailed the feel of the OG but brought it bang up to date.
Doom was a FPS made based in horror media like Evil Dead 2, Aliens and the H.R Giger work, and Dungeons & Dragons, not memes or a Marvel-like lore.
Level design is one of the biggest reasons why classic Doom still holds up even nowadays. There was a lot of criticism against CoD clones using a comparison of a cinematic shooter's level design with e1m1 design, and praise when keycards back in 2016.
Another point is you couldn't know where the next monster will appear because the encounter design variety. Serious Sam and Painkiller are great, but they're not very Doom-like or not soooo old school FPS, and the misconception with them was because the genre changed at the time (military shooters and Half-life-like games were very popular), and specially because, and I'm sorry, the seventh console gen era was mostly a travesty of FPS genre.
Story was just context and nothing else for Doom by choice, and yet Doom 3, Eternal and probably Dark Ages ignored this (being in later games worse in a way because wanting to be far more fast paced games at the same time). I remember when people applauded watching the Doomguy breaking monitors because not caring about nothing but killing demons like the player in 2016, in what sense are more cutscenes, codex collectables and pop up tutorials more consistent with that?
And I'm pretty sure arcade games, light pseudo action RPGs and semiautomatic platformers have nothing to do with Doom basis and don't add anything to it, and yet people dismiss Doom 3 for aping Half-life and System Shock. And btw, yes, horror themes had a big presence in Doom, even in classic games. Heavy metal and killing armies of demons was an important part of course (specially in Doom 2 and Plutonia Experiment) but the same were flickering lights, ominous horror music, surreal nightmarish hellish imagery, being surprised by a dangerous monster appearing in crazy ways, being tense for the next and hearing their creepy noises. Also, even having its badassery and sense of humor, the demon invasion isn't a joke by any means. And I'm not even counting saturn/psx Doom ports and Doom 64.
The original Doom vibe was split with 3, and still it is mostly with nuDoom (more in Eternal and Dark Ages than 2016).
I haven't mention about the modding tools, another important part of Doom's impact and longevity being ignored in Dark Ages, a joke in 2016, and ignored in Eternal until the last year. Even the now so maligned Doom 3 is better in this regard.
And I say all this as someone who enjoyed 2016 and Eternal and planning to replay them. I understand their appeal. 2016 was a very fun and solid FPS appearing in the genre's worst time, Eternal has a demanding and challenging combat system and it's mechanically interesting by its own. Their verticality, inspired by its son Quake, is a great addition, and I'm interested in Dark Ages. Despite all I said Doom still remembers far more of its roots than other western franchises like Tomb Raider for example (not a high bar though). But looking all the historical revisionism about Doom's intended vision based on Brutal Doom and nuDoom games prove how some important things of this franchise are being ignored or misinterpreted. 
