In the article Asian American Panethnicity: Contemporary National and Transnational Possibilities, by Yen Le Espiritu, the author examines the notion of an "Asian" identity in the United States.  This complex analysis includes some of the history, reasons, inconsistencies, innacuracies, pros and cons of the pan-Asian classification.

Years ago, I worked at a trucking company.  One of my co-workers was a woman who had just moved to the U.S. from the Philippines.  There was one day when someone said something about "Asian people"; I don't remember what was said exactly, but it was (I believe) not meant to be negative.  However, my friend was deeply, deeply offended.  She told me she had never heard that word used to describe people, and didn't see how or why the word "Asian" would describe her, a Filipina who had emigrated to the U.S. I explained that, as far as I knew, the term just referred to the continent of Asia, similar to Europe/European, or Africa/African.  She was skeptical, and said that the Philippines are the Philippines, and not Asia.  From this I learned that even though, for example, the Philippines are a member of the Association of Southeast Asian Nations, at least one wonderful person from the Philippines did not ever want to be referred to as "Asian".

http://en.wikipedia.org/wiki/Filipino_peoples

http://en.wikipedia.org/wiki/Philippines