When Concourse C opened, you could not just enter whenever you wanted, You checked in and waited in the central terminal and did not go to your gate until your flight was called. Now that the doors are open all the time, people just walk to their gate and wait instead. Then they get upset when there is no place to sit. The orginal way NW managed access to the concourse seemed much less confusing. Seems like the compliants began when this changed.