Well the thing is we've barely seen any of {Story Mode} and there's a whole studio on it (plus some really talented folks).
Sure, but isn't there a whole talented studio on the space flight component? Motive is still getting on its feet through the Battlefront process (and ultimately has its own title to produce,) I don't know that we can read too much into the Campaign just from the staffing. I'm still very excited to play Story, but everybody buying SF:BF2 should be getting it with an understanding that its primary purpose is as an online multiplayer game, and if the offline and SP modes turn out well (I already like the split-screen features and Arcade mode), all the better.
Find it kind of surprising that they'll openly talk about The Emperor being dead but make no mention of Vader's demise as well. Wonder if it's known that Vader turned at the end.
Others would know Star Wars canon better than I, but if I understand correctly, the Emperor was a revered leader to those loyal to the Empire (and even to general citizens of the Empire, whether they suffer oppression under Empire occupation or thrive in the Empire's version of an economy or just skate by as an under-controlled planet, manipulation of the narrative maintains the Emperor to be the leader they need despite the dark times ... unaware of who has brought down upon them the dark times.) His death was a major event for the entire galaxy.
Darth Vader, however, is just an enforcer. A big-time enforcer, but he walks the galleys of the Death Star and boards ships in raiding parties with fellow troopers. Grand Moff Tarkin bosses him around. Awareness of his "ancient religion" has dissipated over time as the Jedi were stomped out; whatever magical forces were discovered became channeled through technology into weapons, leaving troopers with the same curiosity over how the Death Star murders planets as how their blaster fires laser bolts or how an Inquisitor's laser sword deflects attacks (perhaps there's even a theory among the ranks for how "Vader's glove" throws soldiers around or chokes commanders?) The Emperor is an exalted leader in a private castle somewhere whose presence would be unexpected even on the "ultimate power in the universe", whereas Vader regularly shows up for construction inspection.
Would Inferno Squad have known Vader? I would assume so (the books and eventually the game probably confirm that?), and maybe they even respect/revere him as a leader and conqueror. But in the grand scheme of things, the death of the grand Emperor and the crumbling of their entire Empire was more than enough grief to process at that time.