The reason why Disney takes it's good ole time on construction is complex in the details but simple in concept...
Because they can!!! They can allow Epcot to become my favorite watering hole, They can allow DHS to operate as 1/2 a park, they cannot add an E ticket to their Signature park for years BECAUSE THEY CAN!
People, including myself, will still go...they will still spend money. And Disney will still continue to profit. Through the legacy and years they have built up the company enough that there is no need to go full steam ahead every year. We may not like it but your life would be a lot less stressful if you stop fighting and questioning why and just accept the what...which is Disney can operate the way they do now because they can afford to do so. Stop debating about how much time it should have taken and just accept that which you cannot change
Universal cannot afford to do so and just rest on their laurels. They need to keep pushing and expanding to play catch up. Rather we like it or not that is they truth. I am glad to be able to reap the benefits of Uni's rise and Disney's evolution in this day in age and have not added a single stress line to my brow...