Can you explain in detail why you believe this to be true? Once they hit the natural thickness limits of a keyboard device there really hasn't been any meaningful change. I periodically interact with a range of them and the only thing I can say for a certainty is that the older keyboards feel better and I have to check the system profile to know what the rest of the hardware is like.
I'm not a design expert by any means so I probably can't give as good of a detailed account as others could, but I know when I use my 2015 macbook pro after using my 2018, or after using an XPS or pixelbook, it feels much older than 3 years.
Maybe it's just in my head, as I noted I'm not a design expert, I mostly just know how it "feels." And to me the 2015 design does feel outclassed by most any ultrabook around this year, including modern macbooks.
For sure, as noted I'm all for that. I don't think we need to move back to 2015 to accomplish that though.
High action keyboards will continue to be phased out by thinner devices and more touch. Many will lament it, but I don't see moving back.
By what?
I personally think my 2015 Macbook keyboard feels pretty good. I also spend a heck of a lot more time typing on my Macbook than one-handing it, so the whole "thinness matters more than usage/responsiveness/reliability" thing doesn't really make sense to me as a tradeoff. I can't think of single time I've ever pulled out my Macbook and thought, "this keyboard isn't cutting it anymore."
But even if we decide that 2015 keyboards are all rubbish, other keyboards on other laptops being sold today do not have so many problems that users have literally written software to combat them by suppressing keystrokes. I don't care what design Apple regresses to or who they want to copy, but they need to start copying someone.
To my mind, it's pretty obvious that this is a architectural problem with the core design of butterfly keyboards. After multiple generations of the same problem, it doesn't look like it's a manufacturing defect or an anomaly. It looks like the butterfly keyboard is just plain and simple bad design. Apple wants to talk about being brave, they should be brave enough to throw out the keyboard and put in something else, even if that something else is just a carbon copy of a standard, modern ultrabook keyboard. I understand that the butterfly keyboard was very hard to build, and I'm very impressed with the tech that went into it, but if you want to make an exceptional product you have to be willing to occasionally kill your darlings.
I mean I get why people have preferences for the things you mentioned, but I'd call them appeals to "comfort and familiar" not "state of the art."
Despite various issues with the new mac design, it was a good step forward and by most measures makes the previous generation feel old by comparison. Yes maybe they're over-optimizing for lightness and thinness, but these are indeed important aspects of a portable device and should not be ignored entirely.
They just need to correct the balance a bit more toward the middle, not go back in time.