Personally, having a plan made the trip easier with our young kids. I would never yell at my child over wanting to ride a ride that's not on the plan, like a PP mentioned seeing, but having a plan last trip let us do more with less waiting in lines, less running around, and less standing there going, "Well, what should we do next?" There were definitely times when we changed the plan on the fly - like on our first MK day when the baby fell asleep in the carrier so DW couldn't go on any rides until she woke - or scrapped it altogether if it wasn't working out. But having the plan in the first place definitely made the trip go more smoothly. If it was just DW and myself, we'd be fine just making some ADRs and FP+ and then winging it, but it's not as big a deal for us to criss-cross the park or wait in longer lines than it is to do that with young kids.
Also, re: Touring Plans - I love that it tells me the duration of each attraction! I never would've thought that Small World is 14 minutes long, or Splash Mountain 18 minutes. Knowing that is helpful, especially since we have to Baby Swap the bigger rides.