First off, I'm glad to see that so many people recognize this as a misguided decision that completely misunderstands what DIsney theme parks were designed to be, and why they were and are so meaningful to people. Things need not be insanely popular to provide value and balance to a theme park.
That said, how does the quote go? 'Never ascribe to malice that which is adequately explained by incompetence'. This is not being done because TWDC hates America or US history or education or any of the similar things being claimed here by a few. This is being done because the modern rulers and shakers of Disney do not understand the parks, their function, their history, or what people value, not because they feel, to paraphrase the ideas of some (or at least, the way I am interpreting their ideas), that America is now an offensive, off-limits topic that must be completely expunged from the parks.
No, this is being done because the current leadership sees anything that is not or cannot be directly tied to a Disney IP as out of place in their visions of the parks. If Disney as a company really hated America that much, it would close its parks, or at the very least it wouldn't be actively making efforts to further enshrine an attraction that serves no purpose but to honor a US president, and give it new life by creating the possibility of a dual show featuring another iconic American. This dismissal of the river and its components also fits with something I expressed in the original CBJ changeover thread that represents the uniquely toxic attitude towards attractions at play, particularly in Florida: because almost everything at WDW has Lightning Lane, anything that doesn't becomes seen and treated as little more than a holding area, a glorified lobby. This is that reality playing out. Incompetence, not malice.
It really is sad Walt Disney World in particular does not have anyone in a position of power who seems to understand the parks. The fact that Disneyland kept its river and everything else does speak to there being people around who get the park and value what makes it work. Disneyland has champions; Walt Disney World has none.
Mourn for the fact that the property with the 'blessing of size' is ironically and continually the least creative entity of all and the worst user of space, that this change could very easily be prevented with only *a little* effort, a little consideration, by *one* person valuing the park's history and what makes castle parks tick.
It's genuinely sad and unfortunate, and we should all be mourning the last US old-school river route, and the largest, grandest, only two-island iteration of TSI that ever existed. But we need not throw out the baby with the bathwater by assuming there's some conspiracy at play here. Disney is stupid, and that's really all there is to it with this decision.