It's as simple as this many people don't like change. period.
Time, and the way people remember it, is a funny thing. We've been to WDW many times, and I do things like time how long it take me to get from point A to point B. Yet whenever I post how long it actually takes, I usually get castigated by folks who insist my times are too high. I assure you, I am a quick walker.
I think when many folks complain about 3fp, they are not factoring all the time it took to collect old FP, and how much mental energy it took to coordinate old FP. There were LOTS of times, we'd walk all the way to a FP kiosk just to discover: FP were gone for the day, or the FP return window would not work.
Now you ARRIVE with a FP on your band. (Unless you are one of the folks who needs to go to he kiosk upon park entry. If you are in that category, then you will spend approx. 20-30minutes getting them- depends how long the line is...could be more could be less. that was the estimated wait on MLKjr weekend.)
Also, previously, the FP return line was not immediate. Soarin' waits are historically quite long, even with a FP. With FP+, our waits were mostly under five minutes. (Though we skipped Soarin' this time around.)
A third factor is the advantage of the wristbands all day. That one is harder to measure, but I know the idiots used to annoy me. You know, the folks who get to the front of the line and STILL have their KTTW card still in their wallet. The folks who could not figure out how to use the old turnstiles, the folks who did not have their cards out during emh. The new bands make it easier to access your hotel room when your holding two coffee, when you go to the pool or water parks, and any time when you might otherwise have put your ticket or wristband in your pocket/wallet.
So Yes, FP+ does = change. he gain of FP+ is that you don't spend any time obtaining FP, or trying to obtain FP. Instead, the trade off is that once your FP+ are used, you do trade some of the time gain time in standby lines. For us, I'm confident that we came out ahead.
My two points of comparison are also not equal. My most recent visit was during a fairly busy time. My most recent pre FP+ visits were during relatively low crowd times. Even still, I'd say the new FP+ was a gain.
The only [part of the new system I really hate is the idea that ALL TS meals are now cc holds. That is a loss. I will no longer book arrival day ADR's, will reduce our ADR's, and will trade 180 day ADR's for same day ADR's. (more GF Café and less 1900PF)
Look up old threads on almost ANY change WDW has made in the last five years and you will find LOTS of naysayers. try reading a few posts about the Epcot giant wand, or the change in stroller rental pricing. Now, most of us actually happy that there are less of those giant plastic behemoths clogging walkways in WDW.