Oh please, Salierie! The only thing worse than this article is the provocative heading Slate gives it. To argue that Seinfeld somehow ruined American comedy, as if Mr. Shapiro would have a series in his absence, is beyond ridiculous---it's schadenfreude of the most childish kind.
Whether you like Seinfeld or not, the way people are turning on him in the wake of "Bee Movie" is awful to witness.
That being said (and this is apart from Rosenbaum's tired thesis) Jerry Seinfeld is setting himself up for trouble: between his profoundly unlikeable wife, his much-publicized porche collection, his unfortunate rich-guy arrogance, his recent overly-promotional appearances EVERYWHERE, he's managed to misjudge the public's tolerance for his schtick and has concoted a bad media moment.
He is no longer the underdog or the everyman, and as a result his jokes now have an edge of condescension. The movie doesn't feel like the return of an old friend, but rather like the billionaire in the manion on the hill deigning us with his presence.
But for us to fall for the bait and pounce on his past is below us as the public, and, more importantly, as readers of Slate.

That title was funnier than anything in this guy's stand-up act. Why does this guy think that angry=funny?

While I agree that the author is a bit too much in love with (the idea, at least) of Rick Shapiro, I think his critique of Seinfeld is spot-on. His cultivation of the inconsequential in his humor makes it worse than bland; it is virtually stupefying. I don't think comedy has to be mean or existential, but it does have to have a core of substance to it to make me laugh. Seinfeld has zero substance.

Comparing Seinfeld to Mozart, however, is comedy gold! It does a great job of satirizing the over-hyped nature of Seinfeld's genius!

Lewis Black and Monty Python spring to mind as examples of "angry=funny."

Except that Black's persona is more exasperated than angry--he's not mad so much as he's disappointed to the point of wanting to shake somebody. And Python's humor was rooted in the absurd, with the "anger" that appears in many sketches appearing as an outrageous and surreal alternative to the stereotypically reserved, stiff-upper-lipped English persona. Specifically, that was John Cleese's stock-in-trade in Python (and later in Fawlty Towers), and frequently appeared in the form of the slow-boil (e.g. the pet store patron who gradually loses his cool towards the calm, deceitful proprietor and begins slamming a dead parrot against the countertop like a hammer and screaming "Wakey, wakey!").

While some of Python's writing, especially in their later work, displayed a certain degree of quiet British rage at institutions like organized religion and the remnants of the British class system (see, e.g. The Life Of Brian or The Meaning Of Life), some classic sketches (e.g. the lifeboat sketch, "Superman") aren't angry at all--they're merely bizarre or absurd. And I can think of at least one that derives humor from pathos, of all things ("Nudge-nudge, wink-wink," in which a virgin attempts to hide sexual naievete under a crude veneer of double-entendre).