$ obviously - but the main reason is that the people in charge aren't geeks nor creative nor visionary.
It NEVER made business sense to build the monorail in WDW or DL. Walt did it because it was fun and thought this was a good future for public transportation (As well as the people mover ride).
Heck, during construction of the Contemporary they wanted to pull the monorail track out of the hotel because it was too much of a hassle and Roy forced them to toe the line and figure it out.
The current problems with the monorail is that the trains are... old. Very old. Secondly they're trying to switch to an automated system which they're having issues with.
From a larger viewpoint the monorail cars are at capacity - They need larger cars which will require wider tracks (which also impacts the Contemporary structure) - but more importantly the transportation patterns at WDW are all screwed up now. It used to be that you went to the TTC and that was the nexus for everything. But with the addition of Epcot, DHS, Animal Kingdom, the Epcot resorts, the water parks, etc; and all spread out - They never kept the transportation system up (besides buses) to accommodate. (Ever try getting back from Epcot at close time to the monorail resorts via the monorail? Ick!)
Walt would've had monorail tracks from park to park. Heck, after seeing the Harry Potter train ride, Walt would already have started work on connecting all the parks with interactive train rides like that and upping the sales of park hoppers (Who cares what the scenery looks like when you can just have video displays windows showing what it would look like - just throw down some tracks through the backlots or even utility roads and let the riders experience simulated trips to Pandora, Endor, an animal safari, vintage European towns from the early 1900s, Japanese bullet train. Not only do you up your park hopper sales, you balance out crowd levels at the parks as people find it easier and FUN to hop!
No no... Buses. But it's ok... they're environmental or something...