Linearity is actually something good for the franchise in the long term. Normies nowadays are too dumb to play games that present you with options or let you explore, they just want to play whatever is popular at the moment to fit in and having the game literally be a straight line is perfect to appeal to these people. That's the reason franchises like Metroid and Castlevania died. If Pokemon became like that sales would plummet, same if you removed references to Gen 1. Pic related is a good example, even for how gratingly linear the region is, remove anything Gen 1 and it's gonna sell like shit. People just can't be tasked to use their brain in the slightest anymore. Say what you will about Gamefreak, but they know how the majority of people think.