REAL service dogs are fine, but someone who has a couple of unruly yappy dogs in a bag should be denied. Or there needs to be special sections like you mention where these passengers are located. There was a time when this notion of being a nervous traveler just meant you either got over it, got sedated, or didn't travel. We need to stop accommodating everyone with mental illness or people who are looking to cheat the system by pretending to have mental illness.
RE: Most airlines no longer accept emotional support animals (ESA's)