Simple fact that since the summer of 2002, when I moved to Orlando, Disney parks have increasing become busier and busier each year. Traditionally you would get the "quiet times" before or after holidays, but that really doesn't exist anymore. Yeah it's a little slower but not by alot, like it used to be.
September 2002 after Labor Day I walked onto Space Mountain 6 times in a row, no wait. I had never done that in my life.
Every year since then, the parks have been getting busier and busier. I normally ALWAYS hit all the parks the 2 weeks before Xmas week, to avoid crowds during Xmas week. Well I didn't go this weekend due to the insane crowd levels and all the hotels at/near capacity for the past few weeks.
Even 3 weeks ago, Epcot was PACKED when we went over there for Illuminations.