I completely understood your post, but I still don't agree.
I wonder how many people actually use FP+ for the attractions that you have listed here in the first place... probably not that many IF what you're saying is true and those attractions don't "need" them. You may be right about the motive for providing an option for those, but for families with little kids that may not want to fool with the bigger attractions, some of those may be on their radar more than they would for, say, my husband and me. And some of those attractions arguably could be used for FP+ logically... HM and PoTC both frequently have wait times of more than 30 minutes when I decide to look on my phone at wait times... yes, I'm a dork and I do that because I'm excited about my trip lol. Some of the shows and stuff, sure... but arguably very few rides need a FP+ option EVERY single day. If nothing else, having FP+ options for those attractions may be helping to spread the crowds around, making them more manageable in general.
And nothing would eliminate tiers entirely beyond Disney deciding to eliminate them. Even if they only allowed one advanced FP+ selection per day and one additional one once you enter the parks, they could still set up limits on the combinations of those two passes.
I like the fact that you are looking for ways to address the restrictions on FP+, but I don't think your proposal would solve the issues.