While I agree that planning down to the minute is beyond excessive -- I saw the post this is referring to and raised an eyebrow -- I will say that I think that Disney requires more planning than other vacation spots. DH and I really love to travel, and generally when we do non-Disney destinations, we reserve a hotel and do some research into things in the area we might like to see, but we leave our day-to-day schedule up in the air and leave plenty of time to make new discoveries.
I personally do not think this strategy works very well for Disney newbies or infrequent visitors to Disney. I do not think you need to or should plan your schedule down to the minute, but I think it is helpful to have more of a game plan. I agree with the Unofficial Guide here: "The operational definition of self-discovery and spontaneity at Disney World is the 'pleasure' of heat prostration and the 'joy' of standing in line... We aren't saying that you can't have a great time at Walt Disney World. What we are saying is that you need a plan. You don't need to be compulsive or inflexible; just think about what you want to do before you go."
For instance, my SIL went to WDW for the first time this spring and didn't plan. Someone told her that the Cape May character breakfast was a must do, so she booked it. She was staying at the Wilderness Lodge. She wasn't exactly sure where the Beach Club was, so she took the monorail over to Epcot, then got confused because there weren't any hotels near the Epcot front entrance, so waited for a bus to take her to Hollywood Studios, and then asked around until someone gave her walking directions. She was stressed about missing the meal the whole time, and her two-year-old was hungry and fussy. By the time they got to Magic Kingdom (where they planned to spend their entire day), it was noon and crowds had picked up. They managed to get on three rides the whole day.
Did it ruin their vacation? No. But could they have had a much nicer and less stressful time had they planned more? Heck yeah.
I do not like to plan every aspect of my vacation. On my last trip, I had one ADR and ate quick service the rest of the time. I buy parkhoppers and decide the day before or the day of what park to visit -- and sometimes we change our minds midday! I choose to take my kids out of school so we can visit at a time of year when there are low crowds and short lines, allowing us to have more flexibility.
But I'm not foolish enough to believe that if I got to HS mid-day, I'm going to ride TSMM without at least an hour wait, or that, say, if my kids had their heart set on eating in the castle (either Cinderella's or the Beast's), I could walk up without an ADR. It's a balancing act, and I think most people here plan more than they think... they just already know Disney so well, they don't really even have to think about it.