As stated in this Reason article, waiving the Jones Act is good, but it really needs to be repealed.

http://reason.com/blog/2017/09/28/trump-waives-jones-act-for-puerto-rico-f

For those who don’t want to click the link:

The Jones Act requires any ship traveling from port to port in the United States and its territories be built, owned, and crewed by Americans. Foreign ships can dock once in a U.S. port and cannot bounce from port to port delivering (or picking up) goods.

The Jones Act (actually the Maritime Marine Act of 1920) drives up the prices of everything coming into places like Puerto Rico, as well as reducing the availability of goods. It’s an obsolete relic of protectionism.

EDIT: Sens. McCain and Lee are proposing a repeal for Puerto Rico. Again, why not scrap the damn thing?