Urgent Care Vs. ER?

Are all reductions of emergency room (ER) use good? Reducing ER use has been a stated goal for “bending the cost curve” in U.S. health care for years. And both policy makers and health care system stakeholders are interested in the changes in ER use.  A quick search for recent coverage led to these stories (and many more):

ER Use Dropped As Obamacare Kept Young Adults On Parents' Plans
ER visits down at LA County public hospitals since Obamacare
ER Visits Jump Under ACA
Washington Medicaid ER Visits Down 10% After Launch Of Initiative To Slow Unnecessary Utilization
Medication . . .