Well, some people are genuine film buRAB who can appreciate good cinema e.g. cinematography, use of music, directing, acting, special effects, but are at the same time not overly fond of reading.
If I set out to read every book that is the source of many of the films I highly rate I would go mad.
As it happens I have read the books but can also enjoy the films on their own merit and NOT worry about what is missing, changed, diluted down or altogether invented for the film.