Monorails are very cool, ask your kid do you want to ride the monorail or the bus to Epcot, let's bet on the answer.
True, but are they $100,000,000 cool? Are they cool enough to bring in $100,000,000 worth of new money from paying guests? Are they cool enough to forego some other headline attraction like Expedition Everest? I don't think so.
With absolutely unlimited budgets, anything's possible. But huge upgrades need some common sense cost benefit analysis to justify. Yeah, additional monorails would be cool, but they make absolutely no sense from a business standpoint. It would also be cool to have a monorail from the airport. It would be even cooler to shuttle everyone back and forth from the airport to WDW by helicopter. My kids and I would love all of that, but doing so would be financially disastrous.
For whatever reason, monorails are now ridiculously expensive. We may not like that fact, but we're stuck with that reality. We can then either: (A) Ignore that reality, or (B) Accept that reality and consider the costs and benefits intelligently. When doing (B) intelligently, we're stuck with the inexorable decision that more monorails are not in the cards. Sorry, but that's reality folks.