>>33965890B/W had some fucking dark themes. Alder losing his partner ruined being Champion for him, the subplot of Bianca's father being afraid to let his daughter out into the world [made worse if you believe that one fan-theory about N's Handler], having the player legit wonder about the nature of Trainer/Pokemon interaction and its drawbacks and EVERYTHING about pic related's backstory.
On an IRL level, B/W could have been the start of an amazing trend. The devs wanted to create something that hearkened back to past entries but strove to be its own beast and the level of confidence they put into it was evident in everything from design to music. And the fans despised them for it, leading to them sticking to the same old formula for the future, much to the franchise's peril.