I remember a humorous answer to this question:
"Yes, those are the people who are looking at long lines for everything, who just missed the parade and who didn't know that Splash, Space & Big Thunder Mountains were all down for rehab."
I happen to think that there's a happy medium between "Disney Commando" and "play it by ear". I want to know what park hours are and which parks are AM/PM EMH. I also want to know about any special events; for example, I just realized a few days ago that our May Anniversary trip will be during the Flower & Garden Show, and there things there - concerts, etc. - that we'll want to attend. But I have given up the UG Touring Plans (which are wonderful for those who are strapped for time, or are relative newbies), and the itineraries that have our GPS coordinates planned at 10 minute intervals.
Just like several other fine minds above have said, we too have developed a "there's always next time" attitude - helped in no small part by our DVC ownership at Saratoga Springs Resort & Spa. And regarding PSs - to be honest, DW and I just don't get that big of a thrill out of most WDW restaurants, so we haven't made a PS in years....
Be well!