Well, Goonies, Poltergeist, and Close encounters were written I by Spielberg alone and Indiana Jones was pretty good imo and that was GL's brain child but he had alot of help from Spielberg.
Let me put it this way, when Super 8 was over and the credits started to roll, the first one was WRITTEN BY: JJ ABRAMS, and the first thing I thought was, 'stick to directing JJ.'
I've seen far too many films that were beyond TERRIBLE that were based off of fantastic books, so I still say Spielberg deserves all the credit in the world for what he did. You are correct he's not the creative genius behind creating many of his most epic films but he's the one who brought them to life, which is no small task.
I mean when you think about it, Jurrasic park was a movie about dinosaurs, that could have been such a disaster if put in the wrong hands (See Jurassic park 3)
I googled Close Encounters, there were 5-6 other writers and Spielberg himself called the original screenplay "one of the most embarrassing screenplays ever professionally turned in to a major film studio or director. It was a terribly guilt-ridden story not about UFOs at all." Other writers did a major re-write which Spielberg liked and he then wrote the screenplay based on that idea. It was his baby, his pet project he actually tried to make it before jaws but the story was so different and so bad nobody watned it.
Again I agree lots of really good books become bad movies, directing is obviously not easy.
I'm just saying what made him famous in some cases were films where the entire idea was done by someone else.
And if you read Jurassic Park you will see while it may have been a movie about dinosaurs, it wasn't a book about dinosaurs, it was a book about someone forgetting mans place in the whole scheme of things and learning the hard way what happens when you play god. I've read that the reason the ending is different, as to who dies, is that Spielberg felt his ending allowed for a sequel better than the ending Michael Crichton had originally written did. Crichton did write a sequel, much of which became JP 3 in the movies not JP 2.
JP 2 was also Spielberg and IMHO was a horrible movie precisely because he took the base idea of Crichton's sequel, that there had to be another island with Dinosaurs on it to use as "backups" for the original island. But he then went in a total other direction and the movie was pretty badly reviewed. JP 3 stuck more to the book and was a much better movie again IMHO.
I thought Duel was a great first film for him but it was I think a Tv movie only, 3 films after that 2 TV only and then he made Jaws which made him famous. I think he did a great job with Jaws, but if you've seen the makign of Jaws you know that what he wanted to make and what he did make were entirely different. The shark didn't work correctly so they had to redo the movie making far less use of the actual shark. That's what made it such a great film the shark didn't work, so he found a way to make it scary as hell without actually seeing the shark that much until late in the movie.
he was good enough to make lemonade from the lemons, but his initial idea would likely have been nowhere near as good. It would be interesting to see how his career had turned out if when he made Jaws they were able to get the shark to work.