As I recall the original story, there were some legal rules and requirements that prevented the LCBCC from doing much of anything else.  

December 14, 2016  R-G Saul Hubbard

"Commissioners who backed the quarry stressed that state law allows them only to consider certain negative impacts when weighing a mining application under what is known as a “Goal 5” process. Those potential conflicts include dust, noise and air quality pollution, environmental concerns and transportation issues.
“Welcome to Oregon land use” law, Commissioner Sid Leiken said. “This is a narrow set of criteria we have to decide on.”