Allan Sloan, in a column criticizing the proposed tax on expensive health insurance plans, says that most of the revenue from this tax wouldn't come from the high-cost plans:

A group of economists has issued a letter endorsing both the principles of cost control in the Senate Finance bill and the idea of health care reform more generally. But this is not just any old group of economists. This is an unusually impressive group, including a pair of Nobel laureates and some figures who don't typically weigh in on current policy debates: Kenneth Arrow, Victor Fuchs, Daniel McFadden, Joseph Newhouse. The signatories also cover a pretty broad swath of ideological territory, from the likes of Peter Diamond and Uwe Reinhardt on the left to Katherine Baicker and Mark McClellan on the right. (Baicker and McClellan served in in the Bush administration.)

One apparent purpose of the letter is to focus attention on a pair of controversial proposals within the Senate Finance bill: Imposing a tax on expensive health benefits and strengthening a commission that advises Medicare payment policies. Neither idea is in the House bill; both run afoul of powerful political constituencies. They won't make it all the way through the legislative process without political reinforcement, the kind this letter may provide

But the letter also has a broader significance.