I don't think anyone who doesn't really mind this change is automatically dumbing anything down, if that's what you're implying. It is absolutely possible to understand, hold reverence for, and believe in the importance of what makes Disney special while also not minding if one attraction gets swapped out for another.
Now, I can understand the point of view that the riverboat and the river were a component of the experience and example of what makes it special, but I would argue if removing that one component somehow degrades the overall whole that significantly, then the overall whole was not that strong to start with, and I don't think most if any of us believe that.