> "someone soemwhere has a good reason to oppose something"

Especially since TPP is (in large part) designed to prevent China steamrolling entire industries and crushing foreign economies through shear size and sketchy economic measures. If the negotiations are public China has way more time to react to the measures, either by working around them or by threatening countries until they drop out.

TPP may or may not be a bad thing, but "negotiated in secret" doesn't make it bad.