No one is saying that EPCOT or any other WDW park shouldn't get new rides. People are saying they should get new, original rides crafted to suit that specific park, rides that are of no lesser quality then Rat.
The ride cloning trend is annoying in and of itself because it results in fewer new and interesting attractions. I can go to both DL and WDW for roughly the same cost and effort - how exciting is the MGM makeover when I'll likely experience the EXACT same SWL in DL earlier? The only genuine advantage of the MGM makeover is that I'll be able to ride MMRR a couple years before it opens in DL. Yay? At that point, what will be unique about MGM? Muppets? I love the attraction, but I still suspect its on its way out. Other than that... MGM has nothing unique other then a few lackluster shows that are over two decades old. Wheeeeee... And as to MGM having the original, better versions of the rides, that only seems to apply to ToT.
But this is all missing the point, which is the homogenization of the parks. Disney's parks should not be interchangeable - they should have unique coherent themes. Are DHS in Paris and EPCOT thematically identical? How about MGM and DL? EPCOT and DCA? Then how can a ride be lifted, unchanged, from one park and stuffed into another? They can't - unless theme no longer really matters. Management seems to view almost all the parks as vague collections of IPs with little to make them distinct. People on these boards got mad when park specific napkins went away and when the One Disney program caused the merch on both coasts to be identical. This is the same principle, but on a much, much larger scale.
It's not a coincidence that my favorite park at WDW, the only one I feel approaches the quality of classic Disney, is AK, which boasts an almost entirely original slate of attractions and, largely as a result of this, is thematically coherent. And its not a coincidence that almost everyone agrees the best theme park in the world, Disney or otherwise, is TDS, which has one cloned ride.