There are plenty of attractions to use FP+ on. Yes, the tiers are somewhat weighted when it comes to EPCOT and DHS because there really isn't anything, but if you plan accordingly, depending on the time of year and days of the week you go, you may not need them anyway. That or book one FP and make a B-line for the other same tier ride that you couldn't get the FP for.
The MK has so many options that the tiers make sense, but Disney is in the process of imagining new things to put places so that more can be added to the FP list and thus, solve the problems.
This works as long as you only care about riding the best rides in the park once. Personally, I'd like to ride TSMM more than once on my trip, but there is no way to ride it more than twice in a day unless you are willing to wait over an hour for it.
Well, technically you could ride it 3x if not more... Get a FP, run for the ride at rope drop, use up your fastpasses and get the 4th, 5th, 6th pass at the kiosk if they're available... or if there are late EMH, get in line.
To be able to book, re-book, and re-re-book your favorite ride, won't happen unless you can manage to get past the 3rd required fp reservation/use.
I spent 2 nights, and one EMH night at DHS last trip (early december) at DHS and I never saw a line for TSMM that didn't look ridiculously long. I didn't just look at the posted time, I looked inside at the queue and maybe I was just unlucky, but it looked like an hour wait both nights. I also highly doubt that a 4th FP could be obtained for TSMM day of. Most the time it's not even available the morning of.
I don't understand any of the three questions posed by the OP, so I will abstain.

Too bad one of Disney's main motivation for My Magic Plus is crowd control to maximize attraction capacity... All to keep Disney from having to build new attractions to increase that capacity.
Personally, I'd like to ride TSMM more than once on my trip, but there is no way to ride it more than twice in a day unless you are willing to wait over an hour for it.
This is not correct. We often ride Toy Story 4x during the final hour of operation during our early summer visits.
The key is to ride while Fantasmic is underway and to ignore the posted wait times.
I'm guessing it means people who go to the parks? Guests?Would someone please tell me WTH a parker is?
Yes please! I thought maybe it was the OP's last name.Would someone please tell me WTH a parker is?