It's a fascinating article, especially for someone like me, who only knew of him by reputation. (I wasn't following theater, much less theater criticism, until much later.) I spent last night reading his blog, a recent entry (praise for some shows that are still running and, surprisingly, The Prom), and an appearance on the Dick Cavett show from decades ago.
Simon seems like a caricature, for whom - as the saying goes for a certain political figure - the cruelty was the point. It was the only point. Whatever enthusiasm he had for the work - even of actors - needed to be hidden, because it would ruin his carefully-crafted reputation. (The anecdote in Feingold's piece in which he was "caught" liking something a director had done is revealing.) He was a one-trick pony of vitriol, bigotry, sexism, and anti-gay screeds.
Compare Simon and someone like Sara Holdren, whose love of theater was apparent from the start of her too-brief reviewing career (and who got the gig because she really hated a play and wrote witheringly about it). Or a contemporary like Pauline Kael, whose love of the movies was apparent even when she trashed plenty of films.
There are plenty of times when I wish critics had tougher standards, lest almost everything end up as a New York Times Critics Pick, or local critics who go too easy on new shows. (I have to read between the lines too often.) But Simon was some kind of influential critic in New York for decades doing a tiresome I-hate-everything routine? Didn't people just ignore him?