He died of cancer at age 66. Crichton’s main contribution to TV was creating ER; he wrote the pilot based on a script he’d written in the early ’70s. By the time it was produced, in the early ’90s, he practically ruled popular culture, what with that show and the many successful movies based on his books. You can fault him for a lot of things — see Christopher Buckley’s famous review of Rising Sun for a funny primer on his faults — but he had a real gift for imaginative concepts that people would respond to. Not just premises, but concepts; ER and Jurassic Park and Westworld don’t necessarily have the most original premises in the world, but they’re thought out conceptually in ways that makes them feel new. ER in particular showed how the stale concept of the medical drama could become fresh if fleshed out with more specific details and a greater sense of intensity than previous, more leisurely-paced (and less jargon-filled) doctor shows.
(Update: As pointed out in comments, linked review is not for Rising Sun but for Tom Clancy’s Debt of Honour. I mis-remembered it because it mentions Rising Sun at the top. Sorry about that.)
Plus, he wrote and directed Westworld, without which we would not have the Simpsons “Itchy and Scratchy Land” episode or the many other TV episodes and movies that have ripped it off.