IOne of the main reasons I don't like fp+ is the booking so far in advance...
This is the biggest misconception which (hopefully) people will realize over time. There is no need to schedule attractions days in advance. That's exactly why Disney is applying the limits of 3 FPs per day and tiering some of the attractions; so that rides are NOT fully booked weeks in advance.
Only time will tell exactly how flexible it proves to be but I have every expectation you'll be able to reserve ride times same-day and still have your choice of pretty much any attraction and return time.
FP+: I had to choose between RnRC and TSMM while making my selections. While TSMM is the smarter choice for FP+, having a FP+ for RnRC right before leaving the park (a tradition) will make the majority of our group happier. I explained that I was disappointed that I even had to choose, and suggested they increase HS to at least 2 headliners, and giving the option for both to be on the same ride if that's how I'd prefer to use them. Same for Epcot. And it's not FP+ per se that I don't like, it's the rules and limitations, and these can be improved upon.
Problem is TSM, RnR, Soarin and Test Track simply do not have enough daily capacity for every park guest to ride. Never have...never will.
TSM is the biggest problem on WDW property. At best, it's hourly rider capacity is around 1200. Over a 10-hour operating day (9-7), that's 12000 guests. The park's average daily attendance is more than double that.
With the legacy (old / original) FastPass system, the more informed park guests were able to maximize access to those rides. They knew to arrive early, head straight for TT/Soarin to get FP, get another FP as soon as the 2 hour window arrived, etc.
People who arrived later in the day or didn't properly manage their FastPasses were left in the cold. They still paid $90 to enter the park but either faced long standby waits or didn't get to ride at all.
Not really sure what Disney could do to address the tiering of FastPasses. As I implied above, they won't create a system where TSM and other attractions are booked solid long before the operating day begins. But when you have attractions which can only accommodate half of the park guests--maybe 1/3 or 1/4 on a busy day--people are forced to choose.
It just happens that the FP+ method of forcing a choice is a little more overt than the old system.