There are no Cons, only Pros for hemp's use. You see, any natural growing plants are provided for all lives to user without oversight form others. Hemp and Cannabis is one such plant, Mari Juana you call Mary Jane is a smuggler's code name which is the only reason it is still illegal in some places.
The US Constitution grants all man -- our specie's name -- liberty and the Declaration of Independence say it is man's unalienable right to things which will assist them in their living. Not smoking it but it has many health benefits when eaten without adding heat to it and it's steams can be made into cloth, thus, we have the right to grow, eat and make cloth of it just because it is environmentally produced.