The country is Burma, not Myanmar

Why does the American news media use the name Myanmar instead of Burma? The UK BBC reports:

The ruling military junta changed its name from Burma to Myanmar in 1989, a year after thousands were killed in the suppression of a popular uprising. Rangoon also became Yangon. ...

The change was recognised by the United Nations, and by countries such as France and Japan, but not by the United States and the UK.

A statement by the Foreign Office says: "Burma's democracy movement prefers the form 'Burma' because they do not accept the legitimacy of the unelected military regime to change the official name of the country. Internationally, both names are recognised."

It's general practice at the BBC to refer to the country as Burma, and the BBC News website says this is because most of its audience is familiar with that name rather than Myanmar. The same goes for Rangoon, people in general are more familiar with this name than Yangon.

So the country is popularly known as Burma, and the USA says that Burma is the official name. Isn't that enough? Why would anyone call it Myanmar?

Nevertheless, the NY Times, WSJ, TV networks, etc call it Myanmar. They appear to be making some sort of political statement by doing so, but what? That the UN is more important than the USA? That the military junta ought to crush the pro-freedom rebels? I don't get it. I just see it as anti-Americanism on the part of the major news media.

I should note that not all call it Myanmar. USA Today still calls it Burma.