While there were certainly issues with TPP[0], it would have given us some options in regards to China which we no longer have. AFAIK, that was a large part of the point of TPP.
We could have had Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, Vietnam, and the United States in one trading block. This would have given all of these countries immense leverage when dealing with China.
IMO, cancelling TPP has to be the greatest strategic blunder the USA has made in this century.