If they are looking at congestion, the esplanade is packed from approx 10:45-11:15 am. There are long lines of people waiting to hop. People who are just arriving, or who have single park tickets, don't realize that they can go to the front. Eliminating the park hopping time restriction (hallelujah) will hopefully eliminate that congestion.
If they closed the backlot and started the demo for Avatar next month, we would have had Portos construction on one side and Avatar construction on the other. That would have been a hot mess. Also, there is this whole transportation piece that is being discussed. Whatever transit is taking over for ART, needs a place to drop off for the parks. They need to get moving on the new transit hub before they can start shutting down the current bus drop off.