Well, Mr. Rosenbaum, if you were not blindly supporting someone whose anti-Semitic credentials favor comparably with Julius Striecher and whose foreign policy goals so clearly include allowing a country that wants to annihilate Israel to get nuclear weapons, your protests might seem not quite so pro forma. If you were given the choice to give up your support for Obama or be gassed you would choose gassing. Shocked, indeed!
German Americans didn't have any qualms about fighting Germany. Italian-Americans were not concerned with Mussolini. Maybe American Jews are just trying to be seen establishing their genuine American-ness by coming out against Israel.
Of course, there's a wee logical flaw in that line of reasoning, in that most of us, their fellow Americans SUPPORT Israel. Then again, most Americans are not concerned with noshing with Woodie Allen in the delis of NYC's upper West Side.