The fact of the matter is that "the agreement would reduce 18,000 tariffs. Tariffs on all U.S. manufactured goods and almost all U.S. farm products would be eliminated completely, with most eliminations occurring immediately." [1] Furthermore, we can't realistically ask for the parties to go back to the negotiating table to try to improve the deal. This one was 10 years in the making, which is depressing, but does mean that it's basically this deal or nothing.
[1] https://en.wikipedia.org/wiki/Trans-Pacific_Partnership#Tari...