The worst thing about the TPP is bad for other countries, not us, so it makes sense that most of the American opposition to it would be sort of nonsensical compared to opposition in, say, Japan.
The only people it'll impact adversely (in economic terms at least) are the Chinese. Which I'm not sure we can really call a bad thing. Yes, it honestly won't benefit us all that much, but it will make a substantial impact on other regional economies, which is very much a good thing in both economic and political terms. I'd argue that the main benefit of the TPP is not the direct impact it would have on the American economy but the political consequences of the economic gains made by the other participating countries.
By 'the worst thing about the TPP' I'm referring to the export of the United States' ridiculous copyright regime all around the Pacific Rim.
