My reasoning is that in every decade the Academy has always picked films that don't hold up to history and look ridiculous years later. Throughout the 5-picture years, the academy has a fairly good track record of selecting 1-2 or 1-3 (most people agree that Social Network-Kings Speech-True Grit were all good choices as was No County-There Will Be Blood, Avatar-Hurt Locker, Argo-Lincoln, Crash-Brokeback, Little Miss Sunshine-Departed, Aviator-Million Dollar Baby-Sideways, Mystic River-LOTR) but in slots 3-5, the academy makes arbitrary decisions that could often look stupid down the line.
For example, let's look at 1960. The best picture nominees were Elmer Gantry (worthy), the Apartment (worthy), Sundowners, Sons and Lovers, and Alamo. I'm almost entirely unfamiliar with those films, except I know that the Alamo was heavily campaigned for and yes, ignorance is no excuse for whether a film is good, but there are definitely four unnominated films from that year I've heard of and I'd consider them classics (as with everything on this post, YMMV): Exodus, Inherit the Wind (although some find Stanley Kramer preachy and he never makes a short list of the best directors in comparison to contemporaries like Kazan, Lumet or Nichols, this is among his best films), Psycho, and Spartacus.
Decisions that are stupid in retrospect at the 3-5 slots has happened in every decade.
The 90's, for example, had Awakenings (about as dramatic as an episode of ER), Godfather III (considered to be a disappointment), Four Weddings and a Funeral (80% of Jon Cusack romantic comedies have more to say than that film), Il Postino (clearly has been forgotten: I just asked eight of my facebook friends if they've heard of that, I got ZERO yeses), Secrets and Lies (I got one of eight on that one), Babe (how many films were influenced by that? I think Homeward Bound 2 and Zookeeper was the only other film ever to use the formula of talking animals), the Fugitive (decent for an action film, but even a good action film today like Source Code or Adjustment Bureau is not going to make the Oscars).
It's pretty clear that films like Ed Wood, Misery, The Player, Leaving Las Vegas, Heat, Usual Suspects or Dead Man Walking would have gotten a nomination considering the other awards they got and those films don't look bad in retrospect at all.
In the 00's: Almost Famous, Mullholland Drive, Memento, Royal Tenenbaums, Far From Heaven, Adaptation, About Schmidt, Road to Perdition, Eternal Sunshine, History of Violence, Children of Men, Pan's Labyrinth, Dream Girls, United 93, Into the Wild, Sweeney Todd, Wall-E, Dark Knight, and Wrestler, all had a good chance of being included if they expanded the nominee slate.
Would it have made up for questionable choices like Chocolat? Most definitely. I think more movie fans were happy with 2011's choices than 2000 because all the good nominees god included and Extremely Loud & Incredibly Close (probably the most unpopular choice of Best Picture nominees in the 21st century with Chocolat) will just be seen as a quirky anomaly in retrospect