The thing about (closed-access journal) publishers that ticks people off is just how little of the value they create for their cost. They get the papers they publish for free, they get the peer review for free, they even get most of the editing for free (academic editors are generally volunteer, although copy editors, who check for spelling and formatting, are generally employees).

As for why people keep paying, the answer is industry lobbyists. Whenever there is a movement to require open access of research, industry lobbyists shut it down. Although in many fields like physics and mathematics, people are bypassing journals (closed or open) in favor of preprints.