Being a scientist, I love an exercise in numbers as much as anyone. However, have any of these numbers changed from pre- to post FP+? We're still talking the exact same ride capacity, right?
Personally, I'd rather check in 60 days earlier, find out the only fast pass to Soarin' is at 7PM, rather than get there at rope drop, run to Soarin' (we enter through IG) and find out once we get there the only FP+ available is at 7PM.
Excellent point.
I think we can all agree that whatever a park capacity is, that is what it is and no magic behind a reservation system can increase that.
What all the conjecture and speculation is about could have more to do with psychology, and the point you made may ultimately be the saving grace for WDW - if you can't eliminate the disappointment, see if you can at least minimize it.
In other words - if I go online now to make a reservation for California Grill two months out and there is no availability, I'm somewhat disappointed but the wisdom of my choice is affirmed for me. Wow, it must be good - everyone wants it. So I then embark on a personal endeavor over the next two months to continue to attempt to secure a reservation. Whether I do or not, the experience is much different than if I had walked up to the CG desk at the Contemporary on the day of my visit only to find out there are no tables for that evening. That's a one-shot major disappointment pill that had to be swallowed then and there.
Of course, that's how the psychology works for me - your mileage may vary.
But what I described could be a self-healing process for WDW - reservations for popular attractions reach a point of equilibrium. People will still be disappointed, but in a much different way, a way that might lessen the disappointment because they are made to feel they have additional options.
That's even true, albeit to a much lesser extent, for off-site guests who show up to the park and know nothing about FP+ and learn they need to make three selections from a limited set of options. In many ways the disappointment they might feel at that point is a singular event with a solution, rather than multiple events of disappointment throughout the day as they pass long line after long line with no possible solution.
If you're not convinced, research how yield management has been perfected by the airline industry to keep a certain number of seats filled on every plane yet still accommodate the travel days/times/destination preference of the people who pay to sit in those seats.