Keep in mind those three had just murdered Nerevar, whom I gather she was fond of. Also a good chunk of the Dunmer people forsook her for those three, which has got to grate a bit. Also also, she DID lead a decent number of her followers out of the Red Year mess--witness the enormous shrine they built for her in Skyrim as a thank-you.
That said, I gather the less malevolent Daedric Princes (Azura, Meridia) aren't quasi-benevolent because they like mortals, but more because they like worship (remember the gods get POWER from worship), and have learned that if they keep their followers from being wiped out they tend to get more of it.