I personally feel that the current state of the resort still has a direct connection to the events of 9/11. What took place back then was the fear in Orlando being too much of a destination vacation resort and if travel was curtailed, it would be far too vulnerable if people couldn't commute. This fear caused the extreme caution and hesitation to move forward with any capital projects. What was unfortunately learned during this time by TDO was that they could get away with it. When travel picked back up without the corresponding increase in capital to entice the crowds to the resort - the mold was set. Newton's third law kicked in. Attendance is going up and a budget at rest continues to stay at rest.
Granted, the seeds for this malaise were already being sown in advance of 2001; but, the resulting bounce back in tourism with the minimal expenditures of the resort has simply emboldened them.
At this point, they are actively trying new ways to steer the demand for the resort around (MM+ and now perhaps tiered pricing) instead of embracing what should come naturally with an increase in demand - increasing the supply. Of course doing that would cost money.