I'm very happy to read all the good points said by other users, each of them said things that I would have said too. But I want to add that the old Animal Crossing formula, that is, the one before New Horizons, focused on life simulation, interior design and completing the museum. Only with New Leaf were introduced public works for outdoor decorations. Just think that in the old Animal Crossing games the patterns were used almost exclusively for practical and non-aesthetic use, i.e. to avoid the deterioration of the grass. New Leaf was the game that made the creators of AC understand which direction to take to be successful, it is no coincidence that in New Horizons the patterns created by the community are paid, while in New Leaf you only need a wireless connection to read the QR codes. What I mean is that New Leaf is the pioneer game, together with its spin-off Happy Home Designer, for New Horizons, but the intrinsic formula remains that of the old games, so it's first and foremost a life simulator. And the philosophy of Animal Crossing has always been to "stop" from the frenzy of real life and enjoy the tranquility of this small village surrounded by nature. This doesn't mean you shouldn't set goals, it means that whatever goal you set yourself will take patience and perseverance to achieve it, but you can always time travel like many players do. The programmers put consequences on time travelers but never banned it because it has always been an accepted playstyle since the early days of the series. Everyone enjoys the game as they prefer, but traveling through time to achieve your goals also requires patience and perseverance. New Horizons keeps you busy with Nook miles goals, but at the end it's one big pool where you do the same activities over and over again. In previous Animal Crossing games, you decide your objectives. It's not a game that wants to keep you glued to the screen but wants to make you "stop" for a moment and relax. The whole soundtrack of New Leaf screams "now no more chaos, relax with Tortimer Island, do favors for your animal friends, fish or catch bugs to pay the home loan, decore your house or the town".
With the Welcome amiibo update, external objectives were introduced, which then led to the famous Nook miles. I'm talking about the badges and objectives of the MEOW coupons (but again, they don't want to keep you glued to the screen because once they're done you have to wait until the next day). While badges are really tough objectives, to win a badge you usually have to do that particular activity MANY times. Furthermore, two additional minigames have been added in addition to those on Tortimer Island, which are always there to keep you relaxed and entertained.
Honestly, I'm not a player suited to the New Horizon formula... I want to do favors for my villagers every day because I love interacting with them, having grown up with Wild World, I only want to do what I feel like doing, and I don't want to feel forced to rack up Nook miles for otherwise I can't take a damn boat to get new materials. I want to decorate the town but without feeling stressed by the thousand creative possibilities, because in New Leaf there are many limitations.
Any game that will come after New Horizon... I honestly don't care about the limitations there may be, I just hope that they will return to life simulation as the main aspect, and aim to relax you and not make you burn out.