When you distill film review down to a number of stars, it's not really a review anymore. At that point, you're just answering "is the reader going to like this movie" which really means you're taking into account the likely reader just as much as the film. If you think the reader is going to like anything with explosions and chase scenes, then you're going to give those films lots of stars.

Not saying there aren't critics out there who don't dislike the prequels, but if they didn't write a few paragraphs on the subject, you really have no idea what they actually thought.