If I recall correctly, Disney is putting billions of $ into enhancing WDW ($3.5B?), with Star Wars, Toy Story Land, Epcot development, Tron, etc... as well as a lot of infrastructure. They are adding increased value to the experience and therefore feel justified to increase the ticket price a lot faster than inflation to experience it and pay for it. Between the IT stuff a few years ago (Magic Bands, FP+, MDE, etc) and the recent build outs, they've put many billions into the place.
Whether it's worth the new price and whether Disney invested wisely, only time and people's wallets will tell.