This is purely subjective as I have been reading in these posts. It comes down to what is it that you, the user, desire in any iPhone. For some they are happy with the base model whereas others are primarily focused on top of the line where there are no compromises in performance and features. I get it. I got my 15 Pro Max based on not wanting to compromise on anything and getting the titanium frame. For me this was the epitome of having a premium iPhone and I have been happy with my iPhone since.
What changed for me is form factor, even though my 15 Pro Max is an awesome iPhone, it is heavy compared to the new iPhone air. Looking at the current lineup, I being a Pro Max owner, was not impressed by the build quality of the new Pro series iPhone but that is my preference not yours (everyone reading this post).
For a premium level iPhone I still prefer the use of Titanium for the frame for stronger support and finish. When I saw the new Air, I was enamored with the thinness of this iPhone and that it also had the A19 Pro processor (even with one less GPU core). For my use, the one less GPU core, was not an issue nor not having the vapor chamber in my use case.
As these phones continue to increase in price, I decided to get the 1TB Air which sadly, costs pretty much the same as my 1TB 15 Pro Max did. I don't feel I downgraded with the new iPhone as others here may disagree. For my use case this new iPhone does everything that I have been using an iPhone for so the added features as Pro Raw, which I never used on my 15 Pro Max, is a feature I realize I did not need on an iPhone going forward.
If I had to choose the new iPhone all over again, my choice is very clear . . . I would chose getting a 1TB iPhone Air and would still have it in Space Black. So premium is subjective on what it is that you desire. For me the iPhone Air is a premium level phone that is not quite at Pro level performance and features however is still premium in the choice of materials and footprint. It is an amazing looking and light iPhone that fits right into how I use my iPhone, perfect for me which is all that truly matters.