I agree, the Walt Disney effect. A very basic idea that gets expanded on by many other creative people while the most of the fame stays whith the person who initiated everything.
I think one can read Genes proposal for Star Trek on Memory Alpha (dont have the link at hand now). When you read the proposal you will see how much Star Trek evolved over the years.
Where I think Genes whole achievement is is a very unique mixture of naive and almost childish idealism and an old fashioned faible for adventure together with future gadgets and technology. Especially this humanistic idealism was relatively unique in the sixties.