I will absolutely give you that the game did not come out as a finished product at launch due to the missing holidays. But now that they are back in the game and we have diving and redd. I would say the game absolutely is a "finished product". I'm glad they're adding new stuff to it, but if they never did again, I would still say its without a doubt the best animal crossing they ever made with so much more content than any other game before it.The underlying issue is that after one year, the game isn't even close to what New Leaf provided in terms of content. I'm a huge fan of that game and have been waiting years for a new entry in the series (since the Wii U). Sure, the game is its own thing. But it lacks so many features and includes some really questionable design choices, which just makes it really disappointing, especially as many could be fixed relatively easily and quickly.
Also, we should keep in mind that Nintendo deliberately held back content to later release them as updates. They planned this before/while developing the game. The entire idea of games-as-a-service is centered around the fact that you can release a game with a lack of major features and later release them as updates. It's not as if Nintendo is spending extra time on the game. They gave us an unfinished product and are now finishing it. For us players, this can have the benefit of the developer integrating community feedback and extending the replay value by constantly adding new interesting ideas that want you to keep coming back.
So I would say the rest is just your own personal opinion.