That's all good and well to say, but specifically why abandon a system of producing what our people need and trading with each other to benefit other countries by depending on them for manufactured commodities? 
You are refering to the glory days of the US. The glory days were after WWII when the world's manufacturing base was in shambles except for the US. Further, the glory days had low regulation on business and probably 1/100 as many lawsuits and/or lawyers.
Free trade is the way to go and only looks bad compared to the 1950's which were prosperous times for very different reasons and not protectionism.
That's all good and well to say, but specifically why abandon a system of producing what our people need and trading with each other to benefit other countries by depending on them for manufactured commodities?