"Valve proved to us that Plot is king.. graphics merely enhance this"
uh... nooo they didn't prove graphics just enhance, and can't make games; they were using an old engine so they couldn't, at all, concentrate on graphics. All that was left was plot, and they took the unique (fps wise, anyway; rpgs have done this for years) approach of telling the story as you played via NPCs, radios, or whatever. They proved that without good graphics, one could put one hell of a copied, cliche, all too boring story in, tell the story through events you participate in (no matter how scripted), and draw a player emotionally into the game. That's what made Half-Life for everybody, was the emotional attachment/interpertation of the story. A good example is how much fun I/we/everyone had dealing with the military in Half-Life... those guys were (due to x-files-type stigma) not just mindless enemies, they had the emotional connotation of evil, and thus we all loved killing their hapless asses. Doom, for me, utilised fear to get you into the game, and the simple aspect of survival made that an engrossing game, too.
If you take a look at the doom 3 alpha, simply because of the lights/dark spaces, shadows, glares, blood effects when you get hit which match the attacks, and especially the convincing sounds and realistic animation (feet stick to floor = good), it, even with no story and not one complete level, draws you into the experience emotionally. For that fact alone, doom 3 in my opinion will be good. If they include a story told by the events of the game; events YOU are a part of, doom 3 will show you the power of rock and roll.
So, Half Life, despite it's shit graphics, shitty story, and fairly ho-hum gameplay, kicked ass due to the emotional grip it got on you. Where that emotional grip comes from is irrelevant, and the graphics/sound in doom 3 will certainly provide that grip. Even with no story, you will want to keep playing, just because it invokes an emotional response. Plot isn't king, it is an enhancing factor in a game, but if it can grab your emotions, it can appear to be the most important thing. It seems like it is the "king" because we have never been offered a game which visually evoked a real emotional response; that will soon change.
STAY RIGHT WHERE YOU ARE, GET OUT OF THAT BED AND GET DOWN ON THE FLOOR, GET OUTSIDE RIGHT NOW, RIGHT HERE: GET DOWN ON THE CEMENT, I DONT CARE IF YOU'RE NUDE, GET DOWN ON THE CEMENT, I DON'T CARE IF ITS FREEZING! WHERES THE DRUGS, WE KNOW YOU GOT THE DRU