While I'm not a fan of monorail expansion (I'd like to see something more creative and modern), there is a big problem with a bottom line mentality at a company like Disney.
Imagine how much money Disney could save if they didn't theme the hotels. Simple, concrete buildings would be just as functional as the current resorts. Think how much money they would save and how much they would add to the bottom line.
Does Animal Kingdom need a huge tree? Couldn't they have housed "It's Tough to be a Bug" in a much smaller, less expensive theater?
What about the castle? Just a big waste, isn't it?
Disney is all about creating a fantasy world where things are better than the real world. If they did away with all the things I listed above, how much would their bottom line improve? Maybe a little, on paper short term, but long term it would take away the very product that Disney is selling which isn't amusement park rides, but a whole fantasy world.
When people think of Disney World, they don't think of an amusement park. They think of a clean, friendly, futuristic perfect world. The Monorail has been a key to creating that impression (how many brochures have you seen that feature the monorail prominently?) and if they want to continue the image that attracts people year after year, a modern transportation system would be a big step in the right direction.