Not sure on this, but wasn't tiering always in place from the beginning?
Nope. Tiering was an "improvement" that was added later. I thought you were familiar with all this? How can you definitively state anything is an improvement if you aren't sure of the basis from which it started?
I was not one of the participants in the earliest tests of FP+. But, I thought I read on these boards that some of the earlier tests did have some sort of tiering, then some of the later ones didn't.
When a family member was first able to participate in FP+ testing for a trip in August of 2013, I was a little surprised to see that there was no tiering, but suspected that they didn't need it because the number of participants was low enough and paper FPs were still available. They were also trying to encourage people to participate in the test, so that might have helped.
When I first had a chance to use FP+ as a resort guest for trips in November and December (visiting a daughter who was working as a CM) there were no tiers when we made our reservations 60 days in advance. But, as I remember it, the tiers were put in place for reservations made in November as they were moving pretty quickly through the transition (expanding FP+ to all resort guests, eliminating the "double dipping", removing the paper FP machines, allowing advance reservations for offsite guests, etc.).
So, while it is technically true that tiering was added at some point during the testing/transition phase, it has always been part of the FP+ system when it was available to all guests. I don't really see it as a "change" or an "improvement' because I suspect that Disney always intended to have it at Epcot and DHS once FP+ was fully in place.
I will say that removing tiering is the one change I would most like to see. Selfishly, I don't care because we have always been able to do the things we want to do regardless of FPs. FP+ only makes it easier for us to be sure that we will be able to do our favorite things, and FP+ with no tiers would make it even easier. We almost always stay onsite and I like to plan ahead, so I am confident that I would be one of the ones getting more than one of the attractions that are now in Tier 1 if I want them.
My devious side would get some amusement seeing the initial glee over the removal of tiers turn to a battle as some of those who were upset that they could only get a FP for one of TT/Soarin or TSMM/RNRC find that they now can't get a FP for either. That would really turn into class warfare, primarily between the onsite guests who would be getting the lion's share of those FPs and the offsite guests who would be fighting for whatever, if anything, is left at the 30 day mark.
Because I really don't want to see too many people get upset about not being able to get a FP for either of these attractions, I hope they keep the tiers in place unless and until there is enough capacity to allow them to be removed without creating dramatically disparate experiences for different types of guests. Maybe the addition of more capacity to Soarin and TSMM, or new major attractions, will make tiering unnecessary. But, I really don't see that happening soon because it will probably take several major attractions at each park to get there.