I don't disagree with you but suggest you should consider looking at it as if you were a senior Disney
executive.
Prior to the opening of Carsland, Disney had mixed success creating a buzz with anything smaller than the scale of an entire new theme park. At today's Disney's inefficiencies, developing a 5th Gate would cost billions, much more than NextGen. Even then, the buzz created is fleeting. How many people get excited (for example) to head to WDW in 2013 because of DAK (opened in 1998) or DHS (opened in 1989)?
The buzz (in terms of actual theme park attendance) associated with WDW's most recent success (Expedition Everest) is measured in a few percentage points, about 6.5% at DAK according to TEA's 2007 report. Attendance at Epcot and DHS were up 4.5% that year, suggesting a good portion of the increase might have simply been to a stronger economy (right before the bubble burst). Attendance has been relatively flat since then. Although well received, popular attractions such as Mission Space, Soarin', and Toy Story Mania appear to have been significantly less successful financially. And they we have examples such as the American Idol Experience. At best, Disney executives would have viewed building new attractions as risky investments when the decision was made to green light NextGen.
From a financial perspective, NextGen does not put all of its eggs in one basket. NextGen should help reduce operating expense by allowing Disney to more carefully schedule its resources. NextGen should encourage onsite guests to stay within WDW since they will have guaranteed FP+. NextGen, with preferred benefits for onsite guests, should help with room occupancy and allow Disney to curtail the expensive EMH and "Free Dining" offers. NextGen can be "sold" to inexperienced WDW guests as a way to improve their vacations with guaranteed FP+ and "customized" service. Finally, NextGen permits Disney to collect data allowing for more effective advertising. (Disney's entire advertising budget is almost $2B per year!)
Rather than maybe receiving a one-time bump from a new attraction or land (how is the "New" Fantasyland helping sales so far?
), NextGen allows Disney to optimize the revenue it collects from all 100% of WDW's "guests". A 6.5% attendance increase comes with a corresponding incremental cost. Instead, get the existing guests to spend another 6.5% for what are essentially the same set of attractions and services, well, that's just pure profit.
Perhaps 70-80% of WDW's visitors have visited 3 times or less. For the most part, these folks are too inexperienced to notice quality issues, too enthralled in the moment to notice the imperfections. Experienced WDW visitors might notice these problems but NextGen isn't targeting them. NextGen is targeting WDW's larger "only-a-few-times-in-a-lifetime" guests, guests who are more likely to splurge because their WDW vacations are few and far between.