>>36830768Because it was a nostalgia trip that more or less copied a game people who are jaded to pokemon nowadays remember fondly while only adding minor changes or other things from platinum they loved. It wasn't a bad game by any measure but as someone who looks forward to a big change each gen it was forgettable one time ride.
TLDR; It didn't try anything new or inventive so people can't find a reason hate it, therefore they love it.