They told us when my Kodak digital 6490 camera was 6 mp it was the sweet spot and all you ever needed, then the D40 at 6mp, then 8, then DX 12 mp D300 and FF D3S 12mp, was considered amazing, along came 16 and and out of the blue, wow, 24 mp was considered MF standard, especially when my D3X came out along with its 16 bit blacks.
Then the game went to 36 mp, with a D800 followed by the amazing D800 E pushing the edges further, now we are at 45mp just another hailed sweet spot and all or more than you ever need, Sony is at 61mp and boy is it good.
As all this has moved along glass has progressed and been made to resolve it all, also technology processing buffer etc has all grown in capacity, so is the next sweet spot 60mp Canon is already for releasing in the future 80-100mp.
Ok pixel density is creeping up, what does a DX 24 mp sensor equate in pixel density and that equate to a FF sensor ??? is that 34mp ?
Stacking is the rage look at smart phones now 12 to 40mp but look at the way they achieve it.
At some time very soon the 35mm era will need to move up and Nikon is poised for that.
its a good question you ask, Do we need all this resolution, the answer from my perspective is really no, i am happy with 16mp in my DF or 45mp in my D850, Love the 61mp in the Sony, wow.
With each new change in resolution levels we question things and rightly so, if in the D40 6 MP day someone said 45 and 61mp will be great we would have taken a step back and said hey that not needed, today i shoot my D850 Z8 doing a landscape then do the same with a D4 DF D5 the difference is chalk and cheese.
60 or 80mp is just another progression, look at phones, who needs 40mp in a phone..........or do we to embrace the next world of Ai.
Personally i am happy with my underwater camera being my I Phone 6s 12mp but now i am eyeing of the iPhone 16 pro max or the Google pix pro top of the shelf because of its Ai features.
Cropability is valuable.
But your question and point is true and correct and respected...........i am just going with adapting with the benfits till they no longer exit or excite me, for now.
Only an opinion