>>32572561For me its the general move away from exploration and towards heavy narrative.
Gen 1 and 2 have fantastic worlds that you can basically explore at your own pace after the first few towns, with plenty to see and do and distractions to make along the way.
Kanto opens up after Lt Surge, you can basically tackle any Gym you'd like in any order you like, or go ahead and take down Team Rocket (in FR/LG at least you can do Silph immediately after the Casino if you want, completing almost the entire Rocket sidequest in one fell swoop). Gen 2 was rather linear up to Goldenrod, but even then allowed scope for exploration (ie. you can bypass Whitney entirely and head on to the routes above, and the Bug Catching Contest, if you so choose).
You had an overall goal, a general sense of how to get there, but you were free to roam around more or less as you saw fit. That started to change in Gen 3, with the intorduction fo heavier story elements and "friend" characters who followed you around and gave you tips and advice. This trend continued and came to a complete head in Gen 7, where you are eternally railroaded down whatever path you're supposed to take and never allowed to explore. Every town or route exit will be blocked until you trigger the story event to unblock it (and usually the "blockage" is just a person standing there and not letting you through). Trial Gates are a thing after every town. You basically can't do anything except exactly what the game wants you to at that specific moment.
One great example I can think of is the HAina Desert. It's a completely optional area, with Level-appropriate yet diverse Pokemon inside. The first time you pass it on Route 13, it's blocked off for absolutely no reason. The trigger to unblock it? Beating the next Trial, which is completely unrelated to the Desert, and has no reason whatsoever to affect your access to it. You're just not allowed to go there until the game says you can. It sucks, and its typical of SM.
