I think that people bash the ideas and the writing. The writing is terrible: too wordy (too up-its-own-ass to put it rudely), and the characters too unbelievable: everyone she wants to be a hero is a shining paragon of virtue in all aspects without so much as a single flaw, and whomever she wants to be the bad guys are similarly extreme caricatures of lazy, cheating, and stealing bastards. I'll pass.
Separate to that, her ideas are disliked with good reason.
Well her heroes are heroic and her bad guys are evil or weak — much like superhero films and comics, which are extremely popular and not criticised for the same thing.
But there are interesting characters in her novels that are heroic but undone by their flaws. E.g. Leo Kovalensky and Andrei Taganov in We The Living, Gail Wynand in The Fountainhead, Dr. Robert Stadler and perhaps Eddie Willers in Atlas Shrugged.
Separate to that, her ideas are disliked with good reason.