Very interesting. I think a lot of wanna-be, and professional film critics alike forget one important thing about writing film critiques. And that is, writing a critique is still creative writing. Being a styleless film reviewer certainly won't help boost your career.
An artist looks for a medium to convey their voice. If they choose the medium of writing, they need to be able to distinguish their voice from other artists in the medium.
If everyone uses the same format, it's no longer art. It's repetition.
Like you said, no reader wants to read the synopsis of every movie review. They just want to know the opinion of the reviewer and why.