Wouldn't that logic apply to everything? I mean, upgrading shops was talked about being an end-game goal, but wouldn't you run out of things to buy just the same? The last upgrade of Nook's has Gracie, but her furniture sets are also limited and you are bound to buy everything from the fabulous giraffe at one point. I'm not denying that yes, more Nook Miles items would be great, I'm saying that eventually you will "run out of content" all the same.
For some people, the fact that the stamp is complete is more than enough of an achievement by itself (and thus, an end goal to pursue).
For the record, my sentiment is not that the game is perfect and can't be improved. But what I'm saying is that the perspective of what makes someone happy with the decisions taken is something that is kind of hard for us to know and to provide facts about it- it may simply boil down to the opportunity cost. And to reach the analysis of that opportunity cost, we need information and data that we don't have (maybe it's data that not even Nintendo has although that's more unlikely). The viewpoint and mentality of the developers is also at play here, and we may agree or not with how the limitation on how the game should be played.
This point of yours: "The sheer number of people that have abandoned the game speaks volumes, unfortunately. And to be fair, many of those that have criticized the game in the past, have simply quit playing." is like always, interesting. Do you have any factual evidence of the number of players who have dropped the game? That sheer number you mention. Even more, do you have any factual evidence comparing it to the number of players who dropped previous games at the same timeframe? To add another thing, don't you think it's normal to see more players dropping the game since the game was/is being played by more people? Another thing, if you are basing the volumes spoken because there are people complaining more on social media, don't you think the bigger presence of social media on 2020 compared to previous entries is also at play here?
Regarding the NM, I replied to another user on this same post.
once again, obligatory disclaimer: no, NH is not perfect, yes NH can be improved. yes, you can voice your opinion.