Or they could have kept up with demand by expanding capacity. They chose not to do that and instead are just telling people to spend their money elsewhere.
100 or so posts ago I listed how capacity has increased and is increasing. Building stuff takes time, but I must admit that the pace of the building at WDW is a snail's pace. How long has been Pandora been getting built? Probably far longer than it took to build the original DL and MK.
Anyhow, here's what I see as recent expansions plus new stuff that's going to be opening soon:
1. Fantasyland
2. Soarin's 3rd Bay.
3. All that Nemo and Crush stuff in the Living Seas.
4. After ride interactive stuff in Spaceship Earth.
5. The impending Star Wars and Pixar lands.
6. Pandora at AK.
7. Even River's of Light, which lengthens the day at AK.
8. I believe that daily park hours have been longer overall, but I don't know that for sure.
9. More before and after ride stuff at Test Track.
10. Unique resort features, especially restaurants, that move people out of the park and into the hotels.
11. New Disney Springs, which will have greater capacity (I hear).
Now, I would Iove to see even more? Of course, a 5th gate would be fantastic. But ridiculous crowds are actually a relatively new phenomenon. A billion dollar expansion is not be to be undertaken lightly, and certainly cannot be done in a year or two. Plus, what if the uptick in crowds dies out?
Finally FP+ is probably an attempt to even out the crowds, with attractions being booked in certain times of the day instead of all over. I can now visit a park for a few hours and do those rides I want to do without fighting midday crowds and wandering around waiting for my paper fastpasses to come due. This means I'm gone, not being part of the overwhelming crowd. Instead, I'm chillaxing in the pool, taking a bike ride, or napping for a late night visit once the crowds die down. Before FP+, that would have been much harder to schedule.