One of the reasons for conventional wisdom being wrong could be because many of the details weren't publicly known for decades. The New York Times revealed new details in their 2000 report using a CIA document (Donald Wilber's 1954 after-action report) that was still classified at the time[1]. It's worth looking at Prof. Shaul Bakhash's reaction when these details were released. He found it striking both that the CIA had believed that the coup attempt had failed, and the degree to which Iranians themselves ended up saving the coup attempt[2].

Whether or not Mossadegh could be considered a democratically elected leader at the time of his removal in 1953 is another question. I believe Iran was still using the 1906 constitution, in which the king has the right to appoint and dismiss ministers. Of course, this seems to have been done because of the National Front's electoral victories, so there's a case to be made that his appointment was the result of a democratic mandate. As the article notes, however, by the time of his removal he had become somewhat autocratic[3].

[1] http://www.nytimes.com/library/world/mideast/041600iran-cia-intro.html

[2] https://charlierose.com/videos/18886

[3] http://content.time.com/time/magazine/article/0,9171,858167,00.html

I'd still like my chance to reply to what OP had to say. He brought up some good point and I feel I can explain myself respectfully as part of our healthy and appropriate discourse on your question.

All the factors mentioned (i.e., the widespread hatred for Mosaddegh, Mosaddegh's role in dissolving Iran's democratic process, etc.) don't really matter, they're completely irrelevant.

At the end of the day, the US and UK didn't decide to overthrow Mosaddegh in a coup because he had violated the country's democracy. The US and UK don't really care for the people of Iran and whom they liked and whom they didn't. The events you mentioned in your reply to my original comment meant nothing to the American and British intelligence agencies that engineered the coup. The US and UK both were chiefly motivated by the threat Mosaddegh posed to British economic interests.

It wouldn't be accurate to say that the CIA considered Mosaddegh's wrongdoings when putting together their plan to overthrow him even the slightest because had Mosaddegh not done the things you mentioned, the CIA would still have gone through with their plan to overthrow him.

So I wouldn't see why it's necessary to mention those thing in the article. In fact, I don't think the author overlooks anything because if the events you mentioned played no role in the CIA's choice, it probably wouldn't have to be mentioned in an article discussing the overthrow of Mosaddegh.

Also, the fact that the AIOC had "exploited" oil out of Iran is a widely accepted truth that I don't think you'd be able to refute.