I agree with you that Disney never gives details in advance, at the time, or any historical details. Ever.
But there is where we part ways. There are good websites that provide historical data that they have collected, and have done some analysis, and can give you some good ideas on better park picks not just over know holidays, but comparitavely every week and month.
There are some websites who use (and I think some still do) to predict crowd behaviour due to crowd psychology and external factors. They ABSOLUTELY worked, as I spent many days in the park with small children, walking on almost every ride, and feeling like a salmon swimming upstream at times because we were exiting a ride or land when the masses were coming.
(If you don't think crowd psychology impacts on which park the masses go to, or how it can show to use that knowledge so you don't wait much, to not at all, in line, then I challenge you two tasks. One,:at your resort, on departure early morning, check and see if one of the parks buses waiting spot is overflowing, some with moderate lines, and usually one with not much at all.
Second challenge on crowd mentality- have you ever been to a park before opening, and some turnstiles have 200 people in them and some are completely empty? Walk past the huge lineups to the empty turnstile and wait- in about a minute you will have hundreds of people behind you, and you are at the front of the pack.)
The probably some don't even bother with it comment- I think that is both a yes and no. Certainly a good portion of guests don't even know or understand it. But a lot do: otherwise certain attractions would not max out the FP limits within minutes or less from being available. And as time goes on, more and more people will be using this system, so Disney's data harvesting will only be growing.
I have really not been on the disboards much, have not been for almost five years, but was thinking of going next year with all my kids that are real adults, 21, not just Disney adults. But this thread caught my attention immediately, because I think the observations of these disboarders of what is going on is an indication that Disney is now working on very specific cost saving issues at low crowd times from the very specific data they are harvesting from FP+. As this is my preferred time to go (end of August, low crowds, hopefully free dining) I think it shows me that low crowds are not an indicator of quick standby times anymore.
Hence, understanding crowd patterns from a couple of good websites (paid or free) are a good idea, jmho.
Darn, I'm so long winded so I had to edit to add one more comment regarding the data harvesting. Disney not only has the tool of upcoming FP+ reservations, but now they have years of historical data on exact crowd movements. Those mickeybands- a lot of people wear those in the parks, right? Disney can track every ride, possibly ever meal,snack and souvineer, every visit in to a gift shop even if nothing is purchased, everything. They can see very specifically of the effect of weather on crowd patterns, even to where people go to in the park during the storms or whatever.
They have some serious data, and they will become experts on this data, and how to use it to forecast staff/ food/ souvenirs, everything.