I understand what you're suggesting but view it differently. Having crunched the numbers, I know there simply isn't enough FP+ capacity at most WDW theme parks for "good" attractions. It's probably the main reason WDW is adding FP+ capacity at attractions that don't need them.
Let's pick on Epcot. Most likely, guests will receive one FP+ experience for Soarin', Mission Space, or Test Track. Even combined, these three attractions barely have the capacity to provide one FP+ experience per Epcot guest. Any other FP+ experience I receive for Epcot is going to be a throw-away; a FP+ for an experience that doesn't really need it.
Is one FP+ experience for Soarin', Mission Space, or Test Track enough to keep me from traveling up I-4 to visit a theme park that's presumably adding some amazing attractions every year or two?
Disney's MyMagic+ strategy makes sense as long as the competition sits on its laurels (like WDW has been recently). WDW's competition is not sitting still.
Ultimately, WDW needs things like Avatarland, Carsland, and/or Star Wars Land to compete. Disney management is beginning to accept this, which is why I expect there to be more announcements later this year. Sadly, WDW will have spent north of $1B on NextGen; investment capital that could have been used to build some truly amazing experiences at WDW.