I understand redesigns take time, but they also have multiple prototypes at any given time, and the 2016 was one of many options they went with. I suspect they could have gone with an updated version by now if the problem were anywhere close to what you believe it to be.
Reading what you wrote there..
1. How do you know they had any prototypes that didn't use the butterfly switches?
2. How do you know what other options they'd developed and chose between?
3. "you suspect they could have gone with an updated version" -- that is just complete speculation based upon speculative points #1 and #2
I'm trying to be generous here, but you're working from a narrative of "no big deal" based on as little data as those on the other side, who do in fact have the realities of the repair program and condoms as hard external evidence of acknowledgment of real issues by Apple.
I really think you need to step back and realize that your perspective is that of an echo chamber. Go into those threads. It is you and a handful of others that keep going round and round for pages and pages. Your perspective is skewed.
My perspective on this is from personal anecdotes in both family and work circles, ample podcasts which cover a whole different set of their own circles as well as many writers who've covered this....as well as many developers who are in the Apple sphere and very much not "anti-Apple", who've had issues with their machines.
This forum is only one part of forming my perspective.
We're never going to agree on this, but one thing we can agree on is
"there is some level of problem"
(obviously, as there's a repair program for 2016/2017's and they added condoms to the 2018 models).
Down the road, if I'm wrong, please come back and hold my feet to the fire.
(I'm serious - I will admit to being wrong if I am/was and I will own it)
There will be a redesign (more than the condoms).
They did as Apple always does with these sorts of things.
They deal with it as best they can and alter future plans, and those plans aren't public yet but this could be the year (and is rumored to be).
They've literally done exactly as one would expect given the gravity of this particular issue so far, and they almost never admit wrongdoing of any kind....and there are some good reasons on their end for responding that way actually
(as frustrating as it is).