Clearly it's a personal thing because Philadelphia is such a beloved film. But after Hepburn meets with Stewart and Hussey I find it pretty tough going. Holiday sails from beginning to end. Also I find the whole we've got to bring Kate down a peg or two for the mass audience condescending and a bit embarrassing but obviously they all knew what they were doing. The glamorous glossy MGM look and starry cast doesn't hurt. You're right though that it never gets revived except for the Danner revival decades ago. For such a beloved film which had been a smash hit Broadway play people don't seem to want to see it on stage. Unlike say comedies like You Can't Take it With You, The Man Who Came to Dinner and The Front Page.