Disneyland’s Rivers of America hosts the Mark Twain (which on its maiden voyage hosted the 30th wedding anniversary of Walt and Lillian Disney), the Sailing Ship Columbia, and Fantasmic. None of which applies to MK’s ROA and never has. Not to mention, Disneyland’s has always been more aesthetically pleasing.
I’d certainly imagine the costs of saving MK’s version was a lot higher considering the expansions would need to be built on marginally unsuitable or, at best, marginally suitable land. Disneyland didn’t have that problem and their expansion space was all previously developed land. MK’s river is also connected to a very sophisticated water management system, unlike Disneyland’s.
When you consider all of these factors it’s difficult to justify the continued existence of MK’s Rivers of America. I’m glad WDWMagic insiders have shared that Disney executives chose one of the more expensive plans in terms of making sure the expansion fits in well with Frontierland and Liberty Square.