It's a great loss. He came to NU several years back and I still think about the things he said. He told students that most of his writing didn't take place at the keyboard. Most of his writing happened while he was taking walks at unexpected times. He also said, "If you don't want to write, don't write." That kind of goes against a lot of advice you get about writing daily, all the time, being disciplined, etc. and I think that's why it stayed with me. I think what he meant is that you had to have an inner drive. You also might be writing while doing other things without even realizing it.
He also said something like "This is how I write screenplays. I create a location and then I write, 'Bill Murray does something funny here.'
I love that he underscored that writers sometimes don't have to invent everything, they can collaborate, they can depend on their funny friends and actors to flesh out a screenplay. And yes, it's clear he was influenced by the world of improv.
And you look at his work -- it's still relevant, still funny, still sparking ripoffs and homages and sequels. Animal House is the basis of a lot of teen comedies -- both TV and film. Groundhog Day is still funny and is still talked about in screenwriting classes because of the way it foregrounds structure. I'd argue there could be no Memento without Groundhog Day. Ghostbusters - sure, the funny sci fi action comedy is now a given, but when Ghostbusters was created, he was on new ground.
As a writer, as a director, and as an actor - he was a presence that will be missed.
I didn't know him well, only met him a few times, but he also seemed like a really nice guy too, if that matters. I love that he moved back to the North Shore. . . It made it a more interesting place.
When I write my next screenplay, I'll wish that I could write "Harold Ramis does something funny here" but alas that won't be a possibility. . . again, he will be missed.