The basic problem for many institutions is the difficulty of offending your steady traditional customers while trying to stay vital to new customers. The classic example is in Churches. If you update the Sunday service with guitars and drums, ol' man Peabody and his wife will throw a fit, and write the Church out of their Will and stop dropping their big check in the collection plate every week. But if you stay with the old traditional, no one under 50 shows up.
WDW is an institution, and they've built new parks about every 10 years to keep the new guests interested while maintaining the comforting nostalgia in the old parks (with the occasional new attraction thrown in). The problem is that no new park has been added since the 90s to get cutting-edge guests excited, and new attractions within the old parks indeed have a short shelf life because of the blurring pace of technology.
In the meantime, who has a billion dollars every year to spend on constant upgrades with a shelf life of maybe 10 years? How many new guests will pay more or walk through the gate to make that billion dollar a year investment worthwhile? And can the existing parks handle the additional capacity?
Bottom line: The "whiners" tend to gloss over the above realities. Yeah, brainstorming solutions is fun, but it ends in frustration if the dollars aren't there to make them a reality.
Solution: New gate, and I have to think that it will be Hero-land or Marvel-land once Disney gets the east coast theme park rights to characters. That will bring cutting edge and take in a whole big bunch of paying guests, thus making it economically viable. That's not whining, that's fun brainstorming with a big dose of plausibility.