As PrincessShmoo said, people using Disney transportation from Disney World or the Hyatt at MCO don't have control over when they arrive -- they arrive when the bus does. Rather than make people who arrive on a bus wait outside the terminal for 30 minutes or more, DCL decided to allow them to enter the terminal when they arrive. If a lot of people are expected to arrive by Disney bus, this may result in a small delay for arrival times for people getting to the port on their own.I can completely understand reserving PATs for Pearl and concierge, but since when is DCL transport getting preference?!?
Once boarding begins, it's often less than 5 minutes between boarding groups, so the difference between boarding group 4 and boarding group 8 is probably less than 15 minutes. On my recent Dream cruise, my family had boarding group 6. When we boarded, we were told that the Dining Changes table wouldn't open until 1 pm and Animator's Palate opened for lunch just as we walked up. We could have boarding 30 minutes later and still had a sit-down lunch and time to stop by Dining Changes and Guest Services before staterooms opened.