I don't hate Koepp. The fact is with KOTCS, to me, it wasn't all just the script. This realisation comes with what was written in the novel. The novel indicated some rather good ideas and moments which were I felt needed in the film for a better transformation of characters' development (ie Indy's whole "what happens when I'm gone, who will they say I was" kind of thing).
Koepp has written decent scripts IMHO and as a kid, I absolutely loved "The Shadow". I thought and still think it's a good and entertaining film. "Spiderman" was really awesome too. Maybe he was given more opportunities and more to play with in both as "The Shadow" was a one off and "Spiderman" was the first in the series, so maybe it's when he has to deal with already established series (like JP), such screenplays may not be his strong point as a writer.
Fact is all writers have got some brilliant pieces and some real turkeys. Sometimes I feel that people at the moment, just want to focus on the turkey (I know I do at Christmas!
).
The other fact is (and a lot of people in the public forget this) that a movie is the work of many, many people, not of a sole artist (or director). Sure there are exceptions to the rule, but in general a film is the artistic responsibility of many makers (financial and success rate responsibilities fall on the few, and usually powerful). So if a film sucks, then frankly, I dare say, that you cannot just blame it on one person.
