how many people "need" a beer ....or 8?  your complete pot argument could have been an argument against liquor just substituting. marijuana would be posed to become our new "timber"  income stronger than any other product or service out there.  look how much money it's already generated.  
    the growers greenhouses have few cons as opposed to grass burning lets say... zoning should really look at where the grows are. away from septic systems, wells, creeks , rivers ... neighbors. 
  BTW the feds pay certain people to grow hemp for rope for the Navy -. in georgia i think. it's like the tobacco growers have had the license to do so for generations. the plant is very useful - the bias against marijuana is unfounded. it can be woven for cloth, shredded to make paper, braided together to make rope, the seeds can be eaten. the plant as it is not toxic.