I mean you're very wrong, B/W 2 was a completely different game with a new plot, x/y didn't even have one and Us/um was the exact same game as far as features go (unless you're mad they didn't have mantine surfing in the first one)
-The original had Red/Green in Japan then came out with the superior Blue which is what we got as Red/Blue in the west
-Still haven't played GSC so I'm not sure on how much better Crystal was on the other two
-Emerald was far superior to Ruby/Sapphire
-Diamond and Pearl were horrible Pokemon games everything about it moves at a snail's pace and a ton of the new Pokemon weren't even obtainable until Platinum. Which is so much better that D/P are borderline unplayable
-You're absolutely right on Gen 5 and that's the exception
-X/Y's even worse as a result, because there is no Z. Despite being a remake ORAS had a ton of content and ended up easily being the definitive Gen VI game.
-Still haven't beaten Sun/Moon because of the opening hours being painfully slow, but everyone and their moms have told me to just play Ultra Sun/Moon they're the best ways to play it.
For what it's worth, Sword/Shield have multiple elements to suggest they've been developed with the intent of being the only Galar games. ---