Reading a lot of this stuff is making my head spin.
My trips to WDW over the past ten years have happened in 2012 (May), 2013, 2015, and 2019 (those three all closer to August). The only one of those trips where I had to use the FP+ system was 2019, and I can safely say that was the trip where I felt it was the most difficult to really do anything without being hit with a long wait or some kind of inconvenience.
I recognize there are all kinds of reasons for this beyond "FP+ isn't good" (like the aforementioned fact that as of 2019 the parks were much more packed than even in just 2015), but part of what was fun for my '13 and '15 trips was just going on short notice with my girlfriend and feeling like we got to do just about everything we wanted to without much in the way of issues. The '19 trip was a generous gift from my parents (they wanted to bring the whole family so my baby nephew could get his first trip in), but that was our first "need the wristband" trip and involved a whole lot of sitting around at home and trying to get our website accounts onto the same trip, trying to get the system not to confuse my father and I (same first names), and eventually getting to Magic Kingdom on day one and my girlfriend and I losing a whole chunk of our day because despite all the preparation our wristbands still didn't read as containing our park tickets. Been to Disney over two dozen times in my life, and it was easily the least satisfied I've ever been with a trip there.
I contrasted this in my mind with the trip we also took to SoCal in 2017 and getting to use classic FastPass at Disneyland; again, that wound up being a pretty spur of the moment trip, we got there and spent one day at the original park, and got to do the vast majority of what we wanted to in a very full day, getting plenty of rides in.
All of this just plays into WDW increasingly becoming a high cost "destination resort" instead of a more regular vacation. I don't want to plan out what rides I'm going to do before I go; I don't want to have to think about it beyond the basic strategies I've picked up over the years by just attending; I don't want Disney to try and push and prod me into spending my days there doing things the way they want me to do them, e.g. "spend more time in shops and restaurants spending money, please!" or whatever. I recognize that I don't have kids as of yet, which reduces the overall cost of going for me, but I just can't imagine going down there and spending the kind of money I regularly see people bringing up (e.g. the trips my gf and I took in '13 and '15 cost us a little over $1,000 each for flights/hotel/tickets for 4 or 5 day trips), and a system that would then ask me to pay extra to avoid long lines would be another brick on that load making me a lot less likely to return.
Honestly, what really burns me about this? Take all that ridiculous money put into the FP+ and My Magic systems and just build a fifth gate, or else more greatly expand the main four you already have, and you'll fix a lot of the worst congestion problems. Improve the overall guest experience, give people more options, spread the crowds out...but I think the era of putting an experience together that gets families to want to come back year after year after year is quickly being supplanted by one where the emphasis is getting one-time visitors to drop $10,000 a pop or something. The weirdest part is I think the crowds are justifying a move to the latter, which scares me quite a bit.