I don't think anyone would argue that James Gandolfini had a major film career, or that he is overdue for an Oscar, or anything of that sort. I don't even think he should (or will) win an Oscar this year.
But do I think other actors in Hollywood -- especially those members of SAG and the Academy -- might have him more on their radar this year because of his passing? Absolutely. I know that you are not familiar with The Sopranos, Italiano -- which is fine, I'm not familiar with much tv from other countries myself -- but Gandolfini's work on The Sopranos was a major acting achievement. It was not a recurring role, he WAS the show, a show acclaimed by many to be the greatest in American television history. And yes, it was one role, but it was one role over an entire decade, and the amount of colors the actor showed in that time was remarkable. It was also an incredibly groundbreaking role, as Gandolfini played the kind of complex anti-hero who hadn't really headlined a tv series before, but which has now been a staple of quality tv in the past decade. And his stage work -- in New York and LA -- was also hugely acclaimed, and the one time I saw him live I thought he was a beast of an acting presence. Add to that the fact that he apparently was very well-liked as a human being, and I see an actor whom I think many want to honor with some sort of "goodbye" recognition, and I don't think they'll be splitting hairs over whether his major work was in film or not when a lovely last film performance from him is staring them in the face.
On a broader topic, I would agree that there is very much about popular culture (especially American pop culture) that is horrible. I've noticed lately that the programming on the tvs at my gym -- one entertainment "news" program after another focusing on the daily lives of the most vapid celebrities (many of whom I've never even heard of), the most mundane and saccharine reality tv shows, sitcoms that contain barely a laugh in an entire episode -- is quite far removed from the type of entertainment I would choose to watch. And I guess everything exists on a spectrum, so something like The Sopranos is certainly much closer to that kind of popular culture than, say, a Kiarostami film. But I'm genuinely puzzled at how someone could dismiss The Sopranos's brand of pop culture, and even bother commenting on the Oscars at all. I've found more pleasure in The Sopranos than most movies of the last decade -- if it isn't the kind of storytelling worth rewarding, then very few American films should EVER be nominated for Oscars. I know we all have our gripes with the Academy -- heaven knows, I do -- but to expand upon a point Uri made recently, if one doesn't want the Oscars to recognize mainstream films at all, then the Oscars probably aren't going to be that enjoyable for that person to follow. (Not saying this is you, Italiano. Just trying to make the point that something like The Sopranos is a pretty strong example of the kind of artistic achievement the Oscars are set up to honor, though in a different medium.)
On the lead/support debate, I'd be willing to be a lot more flexible with Gandolfini than, say, Will Forte. Gandolfini does have a sizable part in Enough Said...but it's pretty easy to argue the movie is Julia Louis-Dreyfus's story. I can't think of any scenes in the movie that don't have her in them, but I can think of a lot that don't have Gandolfini. I would argue it's comparable to Léa Seydoux in Blue is the Warmest Color -- she's got a lot of screen time, but Exarchopoulos has significantly MORE, and the movie is definitely structured to be Adele's story. I could see someone making a solid case for Gandolfini in either category -- that won't be the hill I go to die on this year.