Let me preface by saying that I am not trying to argue with you at all and that I know that your remarks about attendance are correct.
I love Disney....I daydream about it and cant wait to immerse myself in the fantasy every year.
But lets be realistic......Disneys rides are superior in all aspects except for absolute thrill.
I don't care how many time you ride btmr or everest or really RnRc...they can not live up to the adrenaline thrill of say a hulk or dueling dragons. These rides are there for viseral thrill only....not much story, not much scenery, just heart pounding, screaming, get off and run around to ride again thrills!
I am the kind of person who needs and loves both....Coaster kinda thrills...Spiderman thrills.....and also Disney completely kinda immersive thriils...i.e ToT, Potc...etc.....
For me a fifth gate of thrill rides would do only one thing....Assure that the extra 2 days out of my Disney Week that i spend at Universal and IoA, would be spent at home on Disney Soil.....Screaming my lungs out on Maleficent "The Ride"