Briefly without a thread drift...Why? What happened last time?
Parking chaos. Half of the eastern seaboard was gridlocked. Seriously, most main roads through WDW became parking lots. People were stuck in their cars for hours. People parked on the verges and walked. Once inside the meet n greets had lines that were hours long. Guests had to choose which one to see and which to abandon. Event shirts ran out before the event started. Traffic management was strained at best. ODV and quick serves ran out of water.
Fireworks were awesome though.