Eh, I'm not so sure that cow's so sacred. Is free trade positive for the American economy? Yes, of course. It moves our country toward a richer, more intellectually-based economy, which should lead to greater quality of life for everyone: fewer shitty jobs building stuff, being hurt by industrial processes, working really really hard to make little money.
I guess I'm going to parrot you a bit here, because I agree with the rest of your point, but what's happening is the second part of that equation, the benefit for the workers and the individuals, is not being met. Our economy is flourishing, but workers who have been displaced are not being supported.
Our rich, rich economy should be able to either 1) train up people who were formerly doing the blue collar work to succeed in an intellectually based economy or 2) provide them with a standard of living given their inability to find good work (the standard income idea).
We are not even attempting to do either.
College costs a fucking shitload and social programs are drying up left and right. Our kids are getting dumber, relatively speaking, so they will be less competitive in a global workplace.
So no, that is not what I would consider a "net positive" as a net positive, in my mind, means that what's happening is good for most people. Clearly, it is not. We shouldn't make it a platitude, because then we don't get to say, "Free trade is clearly good, but if and only if..."