The Mark VIIs were not all that much in terms of new technology. The issues stemmed from poorly designed windows and improperly placing equipment onto chassis that have been running on the beams since the late-1960s.
Opinions are not self validating and "there is a good argument out there" is a weak defense. Even when Disney was committed to making monorails work, they had to be supplemented with other means of transportation. It might not be as cool, but the sad reality is that the most convenient option for guests are the buses. Disney may not be using the muses to their fullest advantage, but they offer the best solution to moving guests.