what didn't you like about SM and USUM? i do feel that the player got little story significance in SM even though i enjoyed Lilly. I think this was fixed in USUM but i dislike the change to Lusamine.
I think X and Y needed more of their lore explored since Zygarde got nearly zero representation despite their only being 3 legendary pokemon. i hope the inevitable remake actually does it some justice plotwise.
I feel like the entire period from XY to LGPE was a slump in quality for Pokemon (and really you can throw BW in with it too, as that was the trend setter for the direction of that era, although BW2 did offer a brief respite from some of the issues that plagued those games before XY doubled down on much of what BW did) and all of those games share similar flaws, with LGPE pretty much being the culmination of everything wrong with that era. The games were all heavily casualized and handholdy. First of all, all of the non-remakes from BW to SwSh were super linear. The older games had some sense of linearity but there were moments when you could wander off the beaten path and explore large swaths of areas or take an alternate route to get the same destination. But not Unova, Kalos, or Alola. They used frequent roadblocks to limit you to one path, usually only the next route and town and maybe a dungeon if you were lucky until you finish whatever the game wanted you to do before moving on, and this continued throughout the whole game. No wandering off and exploring, the progressions was almost 100% scripted from start to finish. The games were also made to be very easy and intentionally lacked extra content to appeal to casuals and later mobile gamers because they thought people just wanted to whiz through the main story and then move on to something else, so a lot of the extra content that we had gotten used to (such as Contests, Secret Bases, the Battle Frontier, the Game Corner, and the Safari Zone) was axed and often wasn't replaced with something comparable so we ended up with less and less to do in the game. They also took multiple measures towards decreasing the difficulty and appealing to casuals such as decreasing trainer roster sizes (I can count how many times you battled a trainer with more than 3 Pokemon with one hand), changing the EXP Share to force all Pokemon to gain EXP, and increasing mandatory tutorials. And then there was tons of nostalgia pandering to try and replicated Gen 1 with things such as only having new Pokemon in BW (but making many of them clones of Gen 1 Pokemon), including popular Pokemon like Pikachu, Charizard, and Mewtwo everywhere and giving them new forms, and only giving Alola forms to Gen 1 Pokemon. And then of course they cap it all off by making RBY the only game so far to get a second remake (and of course, it's a heavily casualized remake that feels like a step backwards from even the original games). There's some good things those games did do, but overall I feel like it was a bad direction for the entire series.
As for SM and USUM specifically, SM's heavy storyline emphasis meant you were constantly getting stopped for cutscenes. There were literally some sections IIRC where you have a cutscene, take a few steps, and then another cutscene. The level design also seemed to get a lot more simplistic, with few alternate paths or areas to wander off and explore in the actual routes. And USUM was a massive disappointment as an updated version, especially when the last game to get an updated version did an entire sequel instead of just a copy/paste third version. But even putting aside that USUM was a third version and not a sequel, there were still issues. For one they really botched the storyline in this version, while other third versions expanded on the game's story and lore this game retconned things, and the retcons made the storyline worse. Most notably, Lusamine went from being driven insane by Nihilego's neurotoxin to just being an extremist that still does insane things for some reason (why is she still freezing Pokemon in stasis exactly?). And IMO, the extra features and gameplay modes weren't quite as good as some of the things that Emerald, Platinum, and BW2 introduced, with many of them (such as Mantine Surfing, the Photo Club, and Ultra Warp Ride) being very shallow and repetitive instead of some of the more involved and multifaceted sidequests that some of the past ones introduced (such as the Battle Frontier, Pokestar Studios, or Join Avenue). There's just very little that USUM did to improve SM that excites me and it feels like they improved the wrong aspects in the wrong ways.
Again, SM and USUM aren't my least favorites, but they are pretty low on my list and I'd probably put them lower than BDSP.