You're kinda making my point for me now. There are no other options at DHS. That's why you need more rides. Having more rides gives people like me (and there are a lot of us APers out there) more choices.
Right now, us Annual Passholders get FastPasses for TSMM because it's the only family ride at DHS.
But, if you make more rides, we don't get that FastPass for TSMM, We get it for Monsters Inc, or Incredibles, or Ratatouille, or whatever, therefore alleviating wait times on TSMM.
The below are assumptions, but think of them more in concepts as opposed to definitive #s.
Toy Story has an hourly capacity of 1100. 70% of which is devoted to Fastpass (770). The park is open 10 hours a day, so 11000 people can ride per day.
7700 ride using Fastpass+ and wait <15 minutes
3300 ride using Standby and wait 45-90 minutes
The park has an average daily attendance of 27,700
27.8% of park guests get to ride Toy Story with less than a 15 minute wait
11.9% of park guests get to ride Toy Story with a wait of 45-90 minutes
60.3% of park guests DO NOT get to ride Toy Story. It is safe to assume that some percentage of the 60.3% of guests wish to ride Toy Story, but probably didn't get or didn't know about Fastpass+ and were unwilling to wait whatever the Standby Wait time was. In many cases, people have a breaking point. Someone might be willing to wait 45 minutes, but not 60.
If you add additional attractions to the park, it doesn't affect the capacity of Toy Story, but may increase the daily attendance. The new attraction may take Fastpass+ demand away from Toy Story, but currently there is more than enough additional demand of guests that likely want Fastpass+, but it isn't available. Adding capacity helps that much more directly.
If you add a 3rd track, hourly capacity is increased to 1650 (in theory it could be higher as the third track very well may
not be ADA compliant so it may load faster).16,500 a day.
11,550 ride using Fastpass+ and wait <15 minutes
4,950 ride using Standby and wait is unknown
The park has an average daily attendance of 27,700 (No new attractions, no new demand, yes it's an assumption, but it would be hard to attribute an attendance increase solely to this type of addition)
41.7% of park guests get to ride Toy Story with less than a 15 minute wait
17.9% of park guests get to ride Toy Story using Standby
40.4% of park guests DO NOT get to ride Toy Story. That # is far more favorable.