The thing that liberals seem not to understand about re-negotiating NAFTA or similar is that any transition to a new state will result in some pain. That something might hurt is not a reason not to do it.
For instance: going to the dentist hurts but is better than letting all your teeth rot.
I am not actually advocating for or against re-negotiating NAFTA here. What I am arguing against is the contention that if something causes any discomfort or even a period of re-organization, that it is therefore not worth attempting.
Curiously, (pseudo) liberals had no problem excusing or even declaiming the merits of all the difficult re-adjustments that occurred and are still occurring due to treaties and other agreements such as NAFTA.
Funny that, huh?