My parents always took us out of school at off-peak times (January in Orlando is splendid when you live in upstate NY) so I grew up spoiled with so many things being walk on. The exception was TGMR the year MGM opened and it was well over an hour.
When I went as an adult before FP, I went when I felt like it, read no guides, and had no touring plan. I expected to wait in lines and I did because, frankly, I was out too late living the single life to get up early on vacation. Basically, I treated it like any other amusement park. Crowds were lower then though.
First time I went and saw FP - in the park, knew nothing about it beforehand - I thought it was lame because I did not want to be tied down to a time and place. The trade off for spontaneity was worth it if it meant waiting in line a little longer and sleeping in. Plus, I always had hoppers and did EMH. The second and third times, I used FP like a master thanks to touring plans/unofficial guide. Ditto for DLR. I loved the challenge of executing perfect strategy. I made it look easy to hubs, so the lack of waiting and amount of attractions we enjoyed impressed him enough to become a Disney lover.
No one likes to wait in lines anymore, especially when you had a stratagy that minimized them. Since an equally successful strategy has not been realized for the new technology, lines are even more intolerable because those that worked the system well have not had to contend with them for many years. I totally get where regular visitors who mastered the old system are turned off by the new one enough to take an uncharacteristic break from the mouse.
We have our first FP+ coming in October and our toddler will be there for his first visit. I am stoked because FP+ makes the rope drop strategy unnessaray for the rides we plan to go on - we never did any of the "little kid" stuff together or before we met. Other than our AK day, I predict a max of 5 hours in the park at a stretch, so having 3 experiences locked in works well for us at THIS stage.
I am going with an open mind, but if it were just me and hubs we would certainly have added on universal/ioa at the expense of WDW time. I have DLR on the horizon for a surprise 2016 trip for my niece and possible DLP for 2019 for her 17th birthday. We will likely not return to WDW until 2020 for a NYE trip, when I imagine there will be a whole different tech. To love or hate.