Because China wants a piece of this amazing pie the US has cooked up. The US gave up the hard-to-automate, labor intensive industries while keeping a lot of the high-margin, highly-automated industries. So while Chinese companies compete for razor thin margins on smart phone components, American companies sell flavored sugar water all over the world for 500% markup (and gobble up any competition).

That's why the TPP is so important, it specifically excludes China because the goal is to further entrench US companies in SE Asia/Oceania. If the US backs out, then that gives China the opportunity to come in and sell the low-cost smart phones AND overpriced sugar water.

We are competing with China for trade partners and it seems backwards to me to forfeit.