I'm not going to list every problem I have with modern Pokémon games, for the list would be far too exhaustive, but while I do agree that a good number of people went far beyond what is necessary to state their disdain for Sword/Shield, I can't disagree more that the quality of the game in any aspect is anything above mediocre, let alone better than the games that came before it. The older games are buggy, suffer from extremely antiquated mechanics, and are built on code seemingly held together with duct tape. But I'd argue they have far more charm, personality, and care than the newer games by a landslide.
Sw/Sh's mechanics are extremely hollow. Now Pokémon are... larger. Yaaaaay? I'm also not a huge fan of the roaming Pokémon as opposed to the random encounter style nature of the older games. Perhaps it's simply nostalgia speaking, but I found that it severely reduced a lot of the mystery and intrigue of entering a new area when you could instantly see which Pokémon you were likely to encounter. It also eliminates the need to make calculated risks based on statistics, which is something that RPG's traditionally thrive in. The keyword here is traditionally, because from what I understand, most games are moving away from this model as technology has improved, but I think a more effective middle ground would be to emulate something like Tales of Symphonia's battle system, where you can see monsters roaming in the overworld, but you can't see what monsters they are until you encounter them. Sw/Sh is also extremely linear compared to previous games in the series, which takes a lot of the fun and element of choice out of exploration.
I actually don't really care too much for the cut content, even though I understand why it's bad enough to be a dealbreaker for many fans of the series. I didn't expect that for a series going on one thousand unique monster designs that we'd be able to just perpetually have every single creature supported forever, and I can't imagine the kind of headache it must be to balance these things out to create a cohesive single-player experience, let alone the nightmare of balancing it out for multiplayer. But I do take issue with the dishonest PR that GameFreak displayed when this was an ongoing issue. This was not an attempt to improve the graphical fidelity, or the quality of the animations, or to make the game more balanced and well-rounded. The Pokémon were cut so they could sell them back to you in the DLC and to force you to maintain a Pokémon Bank account. Trying to frame it as anything else just came across to me as extremely disrespectful. All in all, though, I don't really mind the cut content that much for my own personal enjoyment, but it certainly doesn't aid it, either.
I also don't care about the graphics, but when that was stated as a reason for the necessity of the cut content AND when Bandai-Namco just released a game that looks so much better, with the same IP under the same hardware limitations...
Let's just say it's rough.
The designs of the Pokémon themselves are also kind of weak, in my opinion. Many of them just look extremely generic. The starters are really nice, but the others, I just sort of shrug at. On the flipside, the human designs in Sw/Sh are brilliant, and I absolutely love them. Some of my favorite humans in the entire series.
Finally, in no regard would I say the stories are becoming better with each subsequent game. If anything, they are getting worse. In Gen 3, they raise the hard-hitting question of the relationship between humans and other forms of life, the balance between land and sea, progress versus nature, etc. But they did so in a way that is so bafflingly unrelatable and hairbrained that it can be torn apart with very minimal effort. The remakes are even worse in this regard, with the unfortunate addition of the Delta episode to add insult to injury. (Worth a note, I have watched Tama Hiro's video about the cultural climate that Ruby/Sapphire directly comments on. It's a good video, and it's worth a watch. But while I appreciate the effort and the historical context, I still think it wasn't handled with the greatest of care.)
In Gen 5, they raise the question about the ethics of the core mechanics of the series, and then commits to making no statement whatsoever, before frequently undermining its own narrative with the decision that the only people who would oppose its values are (essentially) terrorists. One particular plot point that always made me sigh a little was when N's entire worldview is completely shaken--years of indoctrination and social conditioning come to light--all because N took the courageous step of... just asking nicely how someone else felt. This mightn't be so bad if the writers put a lampshade on that idea, but they treat it like an inciting incident, so it comes across as extremely weak.
Sw/Sh's story is rather basic, which is fine, but often feels like it's told through the lens of an inactive non-participant. So many NPC dialogue interactions like, "Oh, you should have seen it. But trust me, it was exciting!" Gosh, I wish I could have seen it. It would definitely have been nice.
I will grant you that the stories in more recent games have been more complex. The first two games were more or less about stopping an evil baddy because he's an evil baddy and also becoming the champion and nothing more. But they were at the very least, more or less internally consistent. I feel considerably more accomplished by the end of them than I do in later games, because everything is tied up rather nicely. As the saying goes, sometimes less is more.
Character interactions that are varied and offer dialogue that ranges from amusing to dramatic to just plain bizarre also accomplish the task of creating the feeling that the player has just completed a long journey with many ups and downs. I've long since grown tired of the way the newer games constantly stroke the player's ego, showering them with inordinate amounts of praise at their ability to do even minor gameplay tasks. Not helped that newer games are so easy that the player is literally given legandaries without doing any of the work necessary to obtain them, so the feeling of accomplishment is extremely null.
All this to say that I actually don't think Sw/Sh are bad enough games to warrant a huge amount of disdain for them. If people can like a game that I dislike, then I'm genuinely happy for them. But I don't think the amount of criticism they receive is anything other than completely deserved. I understand that it's not fun having a minority opinion, as there are plenty of things that I enjoy that are often seen as terrible or underwhelming. But it's important to realize that these games don't exist in a vacuum, and that a game's reception can be impacted by both its core elements and in a greater social, cultural, or canonical context.
I started Pokémon in Gen 1, but I wouldn't consider myself a "genwunner" or whatever slang they come up with these days. I like the series fondly enough and have irreplaceable memories growing up with it. But I wouldn't consider the Gen 1 or 2 games to be masterpieces of game design by any means. But I think at least until Gen 4, they were made with a quality standard (relative to their respective time periods) that many of the later games just don't have. I was rather long-winded in my gripes with Gen 5 in a previous paragraph, but I actually quite like that set of games. But when I see them topping lists on "worst Pokémon generations" I can't really help but be empathetic. Because to say they're far from perfect would be an understatement.
tl;dr, Sw/Sh is bad and liking it makes you a terrible person. (I'm kidding)