Matewis: Interesting, though if you are someone that only got into the FPS genre much later than duke3D then I'd expect Doom to have a kind of novel abstractness to it. Duke 3D on the other hand attempts to recreate realistic settings
It's sort of a graphics (or "realism") versus gameplay thing, I believe. And by gameplay I think I mean flow, which someone else brought up already.
Doom doesn't nail it perfectly (there are many community wads that do it so much better, through better level design and tweaked monsters), but it comes close. So close that the classic Dooms remain my favorite shooters of all time, and new releases consistently disappoint me with poor flow & lackluster gameplay. Yes, the flow in Doom is greatly helped by the abstractness of the levels, but I don't think it is the "novel abstractness" per se that makes me like it.
To an extent, Shadow Warrior and Blood suffer from the same lack of flow, likely imposed (at least in part) by the "realistic" environments. The other thing is the enemies. The first thought I have going into Duke 3D is that the enemies are goddamn bullet spongy. In fact, that's how nearly every game after Doom's release feels (Serious Sam being a notable exception).
In Doom, the levels are filled with low tier monsters that you can just chew through with a lowly shotgun or chaingun. Or take down a whole pack of them with the rocket launcher. Yeah there are bullet spongy high tier monsters too, and (except for the cacodemon) these seem to get a healthy dose of dislike from the Doom community. In Duke you get pigs that just duck when you thought they should've died two times over already. Shooting at the same two enemies for so long is a massive interruption to flow. And spending 10 seconds to kill 2 or 3 pigs is nowhere near as satisfying as mowing down a group of 15 imps and zombies. The same feelings underline the flying enemies you meet right in the first level of Duke3D. I just don't find them fun or satisfying to shoot.
Then there's flight? Nah, I'd rather run faster than a rocket on wide open flats (while evading projectiles) than hop from ledge to ledge with a jetpack. A rocket or BFG blast feels more inductive to flow than a pipe bomb that requires you to get close to them and back out...
But yeah, it is the games that get praised for realistic settings that often end up feeling lackluster in terms of gameplay. Take half life for instance. I was as immersed in it as anyone, when it came out. But now that I look at it, the puzzley/objetivey/story segments are boring as hell. The shooting should be fun, except that it's doing what every game preoccupied with immersion is trying to do: give you a bunch of corridors and no more than a handful of enemies to fight at once. Every once in a while. With such design the action is just really boring. Give me one big hectic & fast paced firefight with 50 foes scattered about and I'll be interested. Same goes for Unreal: I absolutely love the music, atmosphere & environment (which I think still holds up today because it's not stuck doing boring earthly realistic places with poor graphics), but the gameplay means fighting a few enemies every once in a while. Nnngh.
Quake has abstract levels but they're just starting to play with 3D and I don't think they have the flow of Doom (unless you learn the levels by heart and speedrun/rocketjump through them... but that's a whole different thing). As other releases from that era, all the enemies (except for the humans, which you see at the beginning of each episode) feel bullet spongy.