Gosh darnit- why do people insist on replying with red font in my quote- it makes it very difficult to reply to...
Even with the old system- if you don't show up at RD on the "10" days you are going to be disappointed. Yes. But there are an awful lot of people who have posted that they just got back and that FP+ enabled them to avoid RD. This will have the inevitable effect of convincing the uninitiated that they can do that too. And if they do that on 8, 9 and 10 days instead of 3 or 4 days, guess what? Disappointment. Just as you predict.
I do feel the need to jump in when posters like you make ridiculous statements that someone will have a miserable vacation. As if people aren't already posting how much they hated their FP+ experience? Forgive me if I am doing nothing more than suggesting that it is possible for others to have a similar experience. Will everyone? Of course not. Never said that. Will the majority? Nope. Never said that either. But your view of the world is that everyone is guaranteed of having a pixie dust and rainbow time, even the folks who sautner in to DHS at 11:00 with FP+s for Muppets, TGMR and F! You don't think that when they see the waits for ToT, RnR and TSm that they might say "Holy crap!" Guess we're not dong those." You and I know that RD is a great equalizer, but not everyone does, and Disney is marketing their FP+ system as a way to "relax" and "lock it in". All I am suggesting is that some people, (and it could be a small, but greater than 0% number) are in for a rude awakening. Somehow, to you, this is a controversial point.
To your last point, NOT AT ALL!! With every change, I revel in the idea that FP+ will become what it should have been all along, somewhat saddened by the fact that the eggheads at Disney couldn't have gotten it right from the get-go. But at least they did the honorable thing and rolled it out in the slow season. Why would if gripe about positive changes? I never once complained about FP-, so why would I complain about FP+ if and when it gets fixed to allow for less restrictive usage? I want the change. I embrace the change. And I am very, very confident that it will change. Seems to me that the people who resist change are the ones who have invested so much time defending the indefensible.
My point is that if this person used to walk in at 11:00 during President's Day, then they see huge advantages to this system. In the past, they would have had no chance of riding the headliners without large lines, now they can at least ride one (plus ST and ToT- and possibly two-three if they know about the work around). This is not the large majority of guests on DIS boards; however, it is the large majority of WDW park guests.
On an off-shoot- when I go to DHS, my goals are to ride RnRc, TSM, Star Tours, and ToT and then get over to EPCOT as quickly as possible Now I can book three FP+'s for these rides at 11:00, 12:00, and 1:00 (I just was able to do it for President's Day, definitely busy season.) In the past, we would RD DHS stay for about an hour and a half and then walk over to EPCOT, now it would actually be possible to us to go to DHS in the afternoon after RD'ing at EPCOT, whereas in the past if we didn't go at RD there was no way we could ride all three of these. This is a potential advantage- FP+ is not the "great equalizer" that RD is; however, it can be used to give you a better experience if you are not a RD fan.
With either of these scenarios, even at a busy time of the year, it is possible to show up at 11:00 and see an improvement over what they've done in the past and leave with a very satisfying experience.
Is it possible that some people will hate their experience? Sure, but I didn't see you warning people that they would hate their experiences when legacy started enforcing return times- there was a big blow up about that too- and at the end of the day it made very little difference.
WDW will continue to tweak FPP just like they did to legacy FP. Legacy FP didn't begin in the iteration that it ended, it went through it's share of growing pains too and it was definitely not a perfect system even at the end of its tenure.
I don't know anyone resisting changes, saying that they would be upset about 6 FP+ or park hopping, etc. Some people are posting why that would not work but no one who is defending FP+ is disappointed when a change like today's is revealed. We like the system now- that doesn't mean there aren't things that can be done to improve it. Rather than telling people that they will have miserable times, I think it would be more productive to tell people strategies to use to make the best use of FPP.
Also, you're pushing it if you're saying that FPP was rolled out during "slow season." To resort guests it was fully rolled out over Christmas. It has definitely been a long rollout- and it's not done yet, things will continue to change.