I definitely agree with you that the frequency of trips has really changed my trips from "gotta get it all done" to a far more relaxing, dare I say vacation-like, experience. Moreover, even just having an AP over daily tickets changes the calculus for where the "worth it" line is and how sad I am if I don't get something done during a trip.
That being said, I think you touched on the crux of one of the arguments that is had over the G+ system with how you described how you are preparing for your once in a lifetime trip. One of the things that has been brought up throughout this thread is the ability of new users to understand and take advantage of the system. Furthermore, an argument that is often brought up is that a Disney vacation requires too much planning or research before you go.
And to that I would ask, why would someone drop thousands of dollars on a once in a lifetime trip and also not do research before they go? To me, that would be like paying thousands of dollars to travel to Europe but then not taking the time to learn how public transit works, how far my hotel is from the attractions I want to go to, or even looking up reviews on restaurants I might want to go to and waiting until I am already there and trying to learn on the fly. Not only does that sound stressful, but also would take away from my enjoyment while I am there because I am on my phone reading yelp reviews and struggling to understand things in a different language.
Yes, I know that Disney is a theme park and not traveling to a different country. But Disney isn't Six Flags either.