I think most of the outrage comes from Disney having created the problem by trying to fix an existing system (old fastpass) that wasn't broken by replacing it with a system that requires (at least for offsite guests) either lines at kiosks or filling out slips of paper to then wait at lines at kiosks.
This gives too much credit to the old system. It had some pretty bad flaws.
1) There was a mad dash to get in the Fastpass line for some attractions and those Fastpasses ran out early, shutting out those who didn't want to be at rope drop. (Yes, admittedly, the best solution to this would be to add more attractions, but even Radiator Spring Racers suffers from this issue, though that ride is worth it, unlike Soarin, but I digress).
2) Fastpass caused constant backtracking as you had to go to the attraction to get the Fastpass. (Yes, FP+ could have been implemented as simply an electronic version of FP, which would have solved that issue without creating others).
3) Environmental.
4) Fairness - it seems the average FP usage was 1.8ish per person, which is very low. Many people didn't get the system and this levels the playing field a bit. (Yes, admittedly, I don't agree with this one, but I live by the motto "stupid should hurt" - others seem to want equality regardless of effort).
It's funny how many people here say they will never step foot in the parks because now they will have to wait in lines. I recall the pre-fastpass days when there were lines for everything. I remember waiting 45 minutes to go on LWTL and 20+ minutes for SSE back in the 80s (but I'd wait 20 minutes for tomorrow's child any day, sigh).
Like the switch from GAC to DAS, FP+ is a huge change and it is going to effect how people tour the parks. Because it doesn't change capacity, it is just a redistribution -- if you find yourself waiting in lines more, that means someone is waiting in them less, so that should make you feel all warm and fuzzy, right?
My main issue with FP+ is the ridonculous 60 day window. I hate, hate, hate how disney wants us to plan every minute of every day so far in advance (and don't get me started on the ADR system). I spend hundreds of hours making charts for where I think we will want to be an every minute of every day, but I have a 2-year old and have no idea what her mood will be when the time arrives. Dinner at O'Hana could be great, or she could be in the middle of a melt-down. For something that supposedly caters to families, Disney seems to have no experience with children and how unpredictable they can be.