Here's the thing though, Disneyland was created with these layers of detail, many of which went consciously unnoticed by guests every visit. I liken it to the Yeti though. Most people don't know that it moves, but their satisfaction with the attraction is lessened whether they know it or not. Universal could have taken an half @$$ed approach with Potter (you could argue this is the Transformers or Despicable Me approach) where they just plop in a Harry Potter attraction in an otherwise unthemed area. The attraction itself very well may still be great, but it would be that much more enhanced in a properly themed area.
Look at Radiator Springs Racers. It's integrated into the fabric of the land. You walk down the street and you see the Cadillac Mountain Range and it enhances the excitement. Look at Tower of Terror in DHS. From the moment you walk into the park you are in an area designed to lead you to Tower of Terror (pre-hat and Frozen banners). That type of placemaking enhances the experience.
You don't have to be familiar with the Harry Potter movies to appreciate the layers of detail in the area. Yes, many of the specific references will be meaningless, but their presence helps surround you in that world. It's why Diagon Alley is the single most wholly immersive theme park land in the world. It doesn't mean that Gringotts is the best attraction, nor does it mean that there aren't better examples of theming elsewhere. But what Diagon Alley does that no other land does is fully integrate you into that world. The structure/design of it completely remove you from the rest of the park. Cars Land doesn't succeed in that, and neither does Hogsmeade. I can't speak for Disney Sea, but my understanding is that there is some bleeding between lands. That doesn't exist in Diagon Alley.