New Horizons is its own game and people often forget that. There's always room to add more stuff into the game but it's not our call nor our vision. The 3DS had lots of content, but imo failed to capture the essence of Animal Crossing. The NPC's were absolutely dull. True, we don't have as many NPC's as we did back in New Leaf, but NL completely cut down all meaningful interaction/backstories with those characters: no interactions with Blathers (he's babbling even returned in this game, which was completely absent in NL), no Able Sisters back stories, etc. Even now, with the returning characters like Harriet or Brewster it looks like we're gonna learn more from them than we ever did in the past games! Even Celeste, while not having her observatory back (which was also removed in New Leaf), at least returned to her roots with the constellations! (Unlike her role in NL which was meaningless).
I'm also saddened to see that many of my favorite features were gone, like the store upgrades. But I'm not upset about it, tbh. True, there were more upgrades before, but our current store holds just as many items as the latest upgrade in the previous games. Besides, a Nookingtons kind of shop wouldn't suit the aesthetics of every island.
I also love some fan favorite NPC's (personally, Gracie, who is also missing and I'm sad to say goodbye to). But Copper and Booker were pretty meh in the past games. Like, WW and CF, all they did was help you connect to your wifi and that was it. Like, I don't feel like being a staple NPC to the game is reason enough to make the cut.
Sure, many villagers are missing but also, the game holds the most villagers EVER in the series with new fan favorites. As for the furniture sets, we've already seen through the direct that many fan favorite furniture sets are returning like the rococo, ranch, sleek, convenience store, etc. The game holds the most amount of furniture in the entire series, so I'm not upset that a few sets are abstent.
NH completely transformed and included game-changing features to the game. You should understand the game for what it is, not hope for the game to become something it's not. Not only are we able to decorate outside, but re-shape our island, make paths, place fences, move our houses/villager houses, move trees, jump through rivers, cook and farm veggies/fruits, make walls/columns in our houses, etc. It's so much that they've added that it's hard for me to go back and fully enjoy previous AC.