>>47893126I wish I could find it (maybe it was in a magazine from my country) but like a decade ago I read an interview where Masuda, promoting Black and White, answered a question literally admitting that they didn't try too hard making Diamond and Pearl great games, because the team thought adding wifi connection to the games would be enough to revolutionize the experience. So DP had almost nothing new or unique beyond wifi; that point alone would make it sell.
Thus he explained that for gen 5 the wifi novelty was not a selling point anymore and they decided to work harder and revise everything from the beginning.
So yeah, DP were made with the minimum necessary effort. I fucking wish I could find the source to share it. It could or not be on the internet.